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\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
International Baccalaureate · PYP 3

Times Tables to 10 × 10

⌚ ~162 min ▢ 18 blocks ✓ 117 exercises ➣ Prerequisites : Times Tables 2, 5 and 10, Times Tables 3 and 4
I Decompose with Addition

We need to find the total for 7 groups of 6 cubes, which is \(7 \times 6\).
Multiplying by 7 directly can be difficult; multiplying by 5 is easier. We know that:
  • 5 groups of 6 cubes have 30 cubes (\(5 \times 6 = 30\)).
  • 2 groups of 6 cubes have 12 cubes (\(2 \times 6 = 12\)).
How can we use these two easy facts to solve the harder problem of \(7 \times 6\)?
Figure

Since 7 groups is 5 groups plus 2 more groups, we can add their totals together. $$\begin{aligned}[t] \text{Total for 7 groups} &= (\text{Total for 5 groups}) + (\text{Total for 2 groups})\\ 7 \times 6&= (5 \times 6) + (2 \times 6)\\ &=30+12\\ &=42\end{aligned} $$ So, there are 42 cubes in total.


Method — The “Break Apart” Strategy
This strategy uses the distributive property: a difficult multiplication can be “broken apart” into two easier ones, and the results added.
For example, to solve \(7 \times 6\), we can break the 7 into a 5 and a 2: $$\begin{aligned}[t] \text{Total for 7 groups} &= (\text{Total for 5 groups}) + (\text{Total for 2 groups})\\ 7 \times 6&= (5 \times 6) + (2 \times 6)\\ &=30+12\\ &=42\end{aligned} $$
Figure
The second number can be broken apart too. To solve \(7 \times 8\), we can break the 8 into a 5 and a 3: $$\begin{aligned}[t]7 \times 8&= (7 \times 5) + (7 \times 3)\\ &=35+21\\ &=56\end{aligned}$$
Figure
Skills to practice
  • Breaking Apart the First Number
  • Breaking Apart the Second Number
II The 6s Times Table

How many dots are there in total on these 4 dominoes?
Figure

We have 4 groups of 6. We can skip-count by 6s: 6, 12, 18, 24.
Figure
$$\begin{aligned}[t]4 \times 6 &= 6 + 6 + 6 + 6 && \text{(counting by 6s: }6, 12, 18, 24\text{)}\\ &= 24\end{aligned}$$ There are \(24\) dots.


Proposition — Times Table of 6
The two columns give the same results: the order of the two numbers does not change the result.
\(\begin{aligned}\textcolor{colordef}{6}\times \textcolor{colorprop}{0}&=\textcolor{olive}{0}\\\textcolor{colordef}{6}\times \textcolor{colorprop}{1}&=\textcolor{olive}{6}\\\textcolor{colordef}{6}\times \textcolor{colorprop}{2}&=\textcolor{olive}{12 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{3}&=\textcolor{olive}{18 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{4}&=\textcolor{olive}{24 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{5}&=\textcolor{olive}{30 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{6}&=\textcolor{olive}{36 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{7}&=\textcolor{olive}{42 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{8}&=\textcolor{olive}{48 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{9}&=\textcolor{olive}{54 }\\\textcolor{colordef}{6}\times \textcolor{colorprop}{10}&=\textcolor{olive}{60}\end{aligned}\) \(\quad \quad\) \(\begin{aligned}\textcolor{colordef}{0}\times \textcolor{colorprop}{6}&=\textcolor{olive}{0}\\\textcolor{colordef}{1}\times \textcolor{colorprop}{6}&=\textcolor{olive}{6}\\\textcolor{colordef}{2}\times \textcolor{colorprop}{6}&=\textcolor{olive}{12}\\\textcolor{colordef}{3}\times \textcolor{colorprop}{6}&=\textcolor{olive}{18}\\\textcolor{colordef}{4}\times \textcolor{colorprop}{6}&=\textcolor{olive}{24}\\\textcolor{colordef}{5}\times \textcolor{colorprop}{6}&=\textcolor{olive}{30}\\\textcolor{colordef}{6}\times \textcolor{colorprop}{6}&=\textcolor{olive}{36}\\\textcolor{colordef}{7}\times \textcolor{colorprop}{6}&=\textcolor{olive}{42}\\\textcolor{colordef}{8}\times \textcolor{colorprop}{6}&=\textcolor{olive}{48}\\\textcolor{colordef}{9}\times \textcolor{colorprop}{6}&=\textcolor{olive}{54}\\\textcolor{colordef}{10}\times \textcolor{colorprop}{6}&=\textcolor{olive}{60}\end{aligned}\)
Skills to practice
  • Counting by 6s
  • Multiplying by 6 using Decomposition
  • Multiplying by 6
III The 7s Times Table

There are 7 days in a week. How many days are there in 4 weeks?

We have 4 groups of 7. We can skip-count by 7s: 7, 14, 21, 28 days.
Figure
$$\begin{aligned}[t]4 \times 7 &= 7 + 7 + 7 + 7 && \text{(counting by 7s: }7, 14, 21, 28\text{)}\\ &= 28\end{aligned}$$ There are \(28\) days.


Proposition — Times Table of 7
The two columns give the same results: the order of the two numbers does not change the result.
\(\begin{aligned}\textcolor{colordef}{7}\times \textcolor{colorprop}{0}&=\textcolor{olive}{0}\\\textcolor{colordef}{7}\times \textcolor{colorprop}{1}&=\textcolor{olive}{7}\\\textcolor{colordef}{7}\times \textcolor{colorprop}{2}&=\textcolor{olive}{14 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{3}&=\textcolor{olive}{21 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{4}&=\textcolor{olive}{28 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{5}&=\textcolor{olive}{35 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{6}&=\textcolor{olive}{42 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{7}&=\textcolor{olive}{49 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{8}&=\textcolor{olive}{56 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{9}&=\textcolor{olive}{63 }\\\textcolor{colordef}{7}\times \textcolor{colorprop}{10}&=\textcolor{olive}{70}\end{aligned}\) \(\quad \quad\) \(\begin{aligned}\textcolor{colordef}{0}\times \textcolor{colorprop}{7}&=\textcolor{olive}{0}\\\textcolor{colordef}{1}\times \textcolor{colorprop}{7}&=\textcolor{olive}{7}\\\textcolor{colordef}{2}\times \textcolor{colorprop}{7}&=\textcolor{olive}{14}\\\textcolor{colordef}{3}\times \textcolor{colorprop}{7}&=\textcolor{olive}{21}\\\textcolor{colordef}{4}\times \textcolor{colorprop}{7}&=\textcolor{olive}{28}\\\textcolor{colordef}{5}\times \textcolor{colorprop}{7}&=\textcolor{olive}{35}\\\textcolor{colordef}{6}\times \textcolor{colorprop}{7}&=\textcolor{olive}{42}\\\textcolor{colordef}{7}\times \textcolor{colorprop}{7}&=\textcolor{olive}{49}\\\textcolor{colordef}{8}\times \textcolor{colorprop}{7}&=\textcolor{olive}{56}\\\textcolor{colordef}{9}\times \textcolor{colorprop}{7}&=\textcolor{olive}{63}\\\textcolor{colordef}{10}\times \textcolor{colorprop}{7}&=\textcolor{olive}{70}\end{aligned}\)
Skills to practice
  • Counting by 7s
  • Multiplying by 7 using Decomposition
  • Multiplying by 7
IV The 8s Times Table

A spider has 8 legs. How many legs do 4 spiders have altogether?
Figure

We have 4 groups of 8. We can skip-count by 8s: 8, 16, 24, 32 legs.
Figure
$$\begin{aligned}[t]4 \times 8 &= 8 + 8 + 8 + 8 && \text{(counting by 8s: }8, 16, 24, 32\text{)}\\ &= 32\end{aligned}$$ There are \(32\) legs.


Proposition — Times Table of 8
The two columns give the same results: the order of the two numbers does not change the result.
\(\begin{aligned}\textcolor{colordef}{8}\times \textcolor{colorprop}{0}&=\textcolor{olive}{0}\\\textcolor{colordef}{8}\times \textcolor{colorprop}{1}&=\textcolor{olive}{8}\\\textcolor{colordef}{8}\times \textcolor{colorprop}{2}&=\textcolor{olive}{16 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{3}&=\textcolor{olive}{24 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{4}&=\textcolor{olive}{32 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{5}&=\textcolor{olive}{40 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{6}&=\textcolor{olive}{48 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{7}&=\textcolor{olive}{56 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{8}&=\textcolor{olive}{64 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{9}&=\textcolor{olive}{72 }\\\textcolor{colordef}{8}\times \textcolor{colorprop}{10}&=\textcolor{olive}{80}\end{aligned}\) \(\quad \quad\) \(\begin{aligned}\textcolor{colordef}{0}\times \textcolor{colorprop}{8}&=\textcolor{olive}{0}\\\textcolor{colordef}{1}\times \textcolor{colorprop}{8}&=\textcolor{olive}{8}\\\textcolor{colordef}{2}\times \textcolor{colorprop}{8}&=\textcolor{olive}{16}\\\textcolor{colordef}{3}\times \textcolor{colorprop}{8}&=\textcolor{olive}{24}\\\textcolor{colordef}{4}\times \textcolor{colorprop}{8}&=\textcolor{olive}{32}\\\textcolor{colordef}{5}\times \textcolor{colorprop}{8}&=\textcolor{olive}{40}\\\textcolor{colordef}{6}\times \textcolor{colorprop}{8}&=\textcolor{olive}{48}\\\textcolor{colordef}{7}\times \textcolor{colorprop}{8}&=\textcolor{olive}{56}\\\textcolor{colordef}{8}\times \textcolor{colorprop}{8}&=\textcolor{olive}{64}\\\textcolor{colordef}{9}\times \textcolor{colorprop}{8}&=\textcolor{olive}{72}\\\textcolor{colordef}{10}\times \textcolor{colorprop}{8}&=\textcolor{olive}{80}\end{aligned}\)
Skills to practice
  • Counting by 8s
  • Multiplying by 8 using Decomposition
  • Multiplying by 8
V Decompose with Subtraction

Now consider \(9 \times 8\). Multiplying by 9 directly can be difficult; multiplying by 10 is easier. We know that:
  • 10 groups of 8 cubes have 80 cubes (\(10 \times 8 = 80\)).
  • 1 group of 8 cubes has 8 cubes (\(1 \times 8 = 8\)).
How can knowing the answer for 10 groups help us find the answer for just 9 groups?
Figure

Since 9 groups is just 1 group less than 10 groups, we can start with the total for 10 groups and simply subtract the one extra group. $$\begin{aligned}[t]\text{Total for 9 groups} &= (\text{Total for 10 groups}) - (\text{Total for 1 group})\\ 9 \times 8 &= (10 \times 8) - (1 \times 8) \\ &= 80 - 8 \\ &= 72 \end{aligned}$$ So, there are 72 cubes in total.


Method — Using Subtraction to Break Apart
This is another way to use the distributive property. It is useful when multiplying by numbers that are close to a multiple of ten (like 8 or 9). To solve \(9 \times 8\), you can think of 9 as \((10 - 1)\): $$\begin{aligned}[t] \text{Total for 9 groups} &= (\text{Total for 10 groups}) - (\text{Total for 1 group})\\ 9 \times 8 &= (10 \times 8) - (1 \times 8) \\ &= 80 - 8 \\ &= 72\end{aligned}$$
Figure
Skills to practice
  • Breaking Apart with a Subtraction
VI The 9s Times Table

There are 9 players on a baseball team. How many players are in 4 teams?

We have 4 groups of 9. We can skip-count by 9s: 9, 18, 27, 36 players.
Figure
$$\begin{aligned}[t]4 \times 9 &= 9 + 9 + 9 + 9 && \text{(counting by 9s: }9, 18, 27, 36\text{)}\\ &= 36\end{aligned}$$ There are \(36\) players.


Proposition — Times Table of 9
The two columns give the same results: the order of the two numbers does not change the result.
\(\begin{aligned}\textcolor{colordef}{9}\times \textcolor{colorprop}{0}&=\textcolor{olive}{0}\\\textcolor{colordef}{9}\times \textcolor{colorprop}{1}&=\textcolor{olive}{9}\\\textcolor{colordef}{9}\times \textcolor{colorprop}{2}&=\textcolor{olive}{18 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{3}&=\textcolor{olive}{27 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{4}&=\textcolor{olive}{36 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{5}&=\textcolor{olive}{45 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{6}&=\textcolor{olive}{54 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{7}&=\textcolor{olive}{63 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{8}&=\textcolor{olive}{72 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{9}&=\textcolor{olive}{81 }\\\textcolor{colordef}{9}\times \textcolor{colorprop}{10}&=\textcolor{olive}{90}\end{aligned}\) \(\quad \quad\) \(\begin{aligned}\textcolor{colordef}{0}\times \textcolor{colorprop}{9}&=\textcolor{olive}{0}\\\textcolor{colordef}{1}\times \textcolor{colorprop}{9}&=\textcolor{olive}{9}\\\textcolor{colordef}{2}\times \textcolor{colorprop}{9}&=\textcolor{olive}{18}\\\textcolor{colordef}{3}\times \textcolor{colorprop}{9}&=\textcolor{olive}{27}\\\textcolor{colordef}{4}\times \textcolor{colorprop}{9}&=\textcolor{olive}{36}\\\textcolor{colordef}{5}\times \textcolor{colorprop}{9}&=\textcolor{olive}{45}\\\textcolor{colordef}{6}\times \textcolor{colorprop}{9}&=\textcolor{olive}{54}\\\textcolor{colordef}{7}\times \textcolor{colorprop}{9}&=\textcolor{olive}{63}\\\textcolor{colordef}{8}\times \textcolor{colorprop}{9}&=\textcolor{olive}{72}\\\textcolor{colordef}{9}\times \textcolor{colorprop}{9}&=\textcolor{olive}{81}\\\textcolor{colordef}{10}\times \textcolor{colorprop}{9}&=\textcolor{olive}{90}\end{aligned}\)
Skills to practice
  • Counting by 9s
  • Multiplying by 9 using Decomposition
  • Multiplying by 9
VII The Full Multiplication Grid
Proposition — All Times Tables from 1 to 10
This grid shows all the times tables from 1 to 10 in one place. To find a product such as \(7 \times 8\), find the row for 7 and the column for 8: the result is in the cell where they meet. The grid can also be read backwards: for \(7 \times \square = 42\), go along the row for 7 to \(42\), then up to the top of its column: \(6\). So \(7 \times 6 = 42\).
\(\times\) \(\textcolor{colorprop}{1}\) \(\textcolor{colorprop}{2}\) \(\textcolor{colorprop}{3}\) \(\textcolor{colorprop}{4}\) \(\textcolor{colorprop}{5}\) \(\textcolor{colorprop}{6}\) \(\textcolor{colorprop}{7}\) \(\textcolor{colorprop}{8}\) \(\textcolor{colorprop}{9}\) \(\textcolor{colorprop}{10}\)
\(\textcolor{colordef}{1}\) \(\textcolor{olive}{1}\) \(\textcolor{olive}{2}\) \(\textcolor{olive}{3}\) \(\textcolor{olive}{4}\) \(\textcolor{olive}{5}\) \(\textcolor{olive}{6}\) \(\textcolor{olive}{7}\) \(\textcolor{olive}{8}\) \(\textcolor{olive}{9}\) \(\textcolor{olive}{10}\)
\(\textcolor{colordef}{2}\) \(\textcolor{olive}{2}\) \(\textcolor{olive}{4}\) \(\textcolor{olive}{6}\) \(\textcolor{olive}{8}\) \(\textcolor{olive}{10}\) \(\textcolor{olive}{12}\) \(\textcolor{olive}{14}\) \(\textcolor{olive}{16}\) \(\textcolor{olive}{18}\) \(\textcolor{olive}{20}\)
\(\textcolor{colordef}{3}\) \(\textcolor{olive}{3}\) \(\textcolor{olive}{6}\) \(\textcolor{olive}{9}\) \(\textcolor{olive}{12}\) \(\textcolor{olive}{15}\) \(\textcolor{olive}{18}\) \(\textcolor{olive}{21}\) \(\textcolor{olive}{24}\) \(\textcolor{olive}{27}\) \(\textcolor{olive}{30}\)
\(\textcolor{colordef}{4}\) \(\textcolor{olive}{4}\) \(\textcolor{olive}{8}\) \(\textcolor{olive}{12}\) \(\textcolor{olive}{16}\) \(\textcolor{olive}{20}\) \(\textcolor{olive}{24}\) \(\textcolor{olive}{28}\) \(\textcolor{olive}{32}\) \(\textcolor{olive}{36}\) \(\textcolor{olive}{40}\)
\(\textcolor{colordef}{5}\) \(\textcolor{olive}{5}\) \(\textcolor{olive}{10}\) \(\textcolor{olive}{15}\) \(\textcolor{olive}{20}\) \(\textcolor{olive}{25}\) \(\textcolor{olive}{30}\) \(\textcolor{olive}{35}\) \(\textcolor{olive}{40}\) \(\textcolor{olive}{45}\) \(\textcolor{olive}{50}\)
\(\textcolor{colordef}{6}\) \(\textcolor{olive}{6}\) \(\textcolor{olive}{12}\) \(\textcolor{olive}{18}\) \(\textcolor{olive}{24}\) \(\textcolor{olive}{30}\) \(\textcolor{olive}{36}\) \(\textcolor{olive}{42}\) \(\textcolor{olive}{48}\) \(\textcolor{olive}{54}\) \(\textcolor{olive}{60}\)
\(\textcolor{colordef}{7}\) \(\textcolor{olive}{7}\) \(\textcolor{olive}{14}\) \(\textcolor{olive}{21}\) \(\textcolor{olive}{28}\) \(\textcolor{olive}{35}\) \(\textcolor{olive}{42}\) \(\textcolor{olive}{49}\) \(\textcolor{olive}{56}\) \(\textcolor{olive}{63}\) \(\textcolor{olive}{70}\)
\(\textcolor{colordef}{8}\) \(\textcolor{olive}{8}\) \(\textcolor{olive}{16}\) \(\textcolor{olive}{24}\) \(\textcolor{olive}{32}\) \(\textcolor{olive}{40}\) \(\textcolor{olive}{48}\) \(\textcolor{olive}{56}\) \(\textcolor{olive}{64}\) \(\textcolor{olive}{72}\) \(\textcolor{olive}{80}\)
\(\textcolor{colordef}{9}\) \(\textcolor{olive}{9}\) \(\textcolor{olive}{18}\) \(\textcolor{olive}{27}\) \(\textcolor{olive}{36}\) \(\textcolor{olive}{45}\) \(\textcolor{olive}{54}\) \(\textcolor{olive}{63}\) \(\textcolor{olive}{72}\) \(\textcolor{olive}{81}\) \(\textcolor{olive}{90}\)
\(\textcolor{colordef}{10}\) \(\textcolor{olive}{10}\) \(\textcolor{olive}{20}\) \(\textcolor{olive}{30}\) \(\textcolor{olive}{40}\) \(\textcolor{olive}{50}\) \(\textcolor{olive}{60}\) \(\textcolor{olive}{70}\) \(\textcolor{olive}{80}\) \(\textcolor{olive}{90}\) \(\textcolor{olive}{100}\)
Skills to practice
  • Multiplying by 1 to 10
  • Reading the Tables Both Ways
VIII Going further
Skills to practice
  • Completing Times Tables
  • Quiz