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International Baccalaureate · PYP 2

Money

⌚ ~82 min ▢ 8 blocks ✓ 35 exercises ➣ Prerequisites : Numbers to 1000, Addition to 100 and beyond, Subtraction to 100 and beyond, Multiplication, Money
I Cents
Definition — Cent
Dollars can be broken into smaller parts called cents. Cents are used to pay for things that cost less than one dollar, or for what is left over after the dollars in a price.
1 dollar = 100 cents (100 c)
Definition — Cents
Here are the most common US coins:
Name Value Coin
Half dollar 50 cents Figure
Quarter 25 cents Figure
Dime 10 cents Figure
Nickel 5 cents Figure
Penny 1 cent Figure
Example
How much money is there?
Figure Figure Figure Figure

  • We sort from the biggest coin to the smallest, then count on: \(50\), then \(50+25=75\), then \(75+10=85\), then \(85+5=90\).
  • \(50~\text{c} + 25~\text{c} + 10~\text{c} + 5~\text{c} = 90~\text{c}\). There are \(90\) cents.

Example
How much money is there? Give the answer in dollars and cents.
Figure Figure Figure

  • Count on: \(50\), then \(100\), then \(110\). There are \(110\) cents.
  • \(100\) cents make \(1\) dollar, so \(110~\text{c} = 100~\text{c} + 10~\text{c}\): there is \(\dollar 1\) and \(10\) cents.

Skills to practice
  • Making an Amount with Dollars and Cents
  • Counting Coins to Make Amounts
  • Adding Coins to Find Total Amounts
II Paying with Cents: Enough and Change
Method — Do I Have Enough?
  1. Count your money: Find the total you have.
  2. Look at the price: Find how much the item costs.
  3. Compare: If your money is the same as the price or more, you can buy it. If it is less, you cannot.
Example
Su has these coins. An ice cream costs \(\dollar 1\). Does she have enough?
Figure Figure Figure   Figure

  • Count: \(50\), then \(75\), then \(100\). Su has \(100\) cents, that is \(\dollar 1\).
  • Look at the price: the ice cream costs \(\dollar 1\).
  • Compare: \(\dollar 1\) is exactly the price. Su has enough: she can buy the ice cream, and nothing is left.

Example — Number of Coins or Value?
Tom has three \(\dollar 2\) bills. Nour has fifty \(10\)-cent coins. Nour says: “I have more money, I have fifty coins.” Is she correct?
\(3 \times\) Figure
\(50 \times\) Figure

Count the value, not the coins. Tom: \(3 \times 2 = 6\), so \(\dollar 6\). Nour: ten \(10\)-cent coins make \(\dollar 1\), so fifty make \(\dollar 5\). Tom has more. In the same way, \(\dollar 12\) is more than \(60\) cents even though \(12\) is smaller than \(60\): \(\dollar 12\) is more than \(\dollar 1\), and \(60\) cents is less than \(\dollar 1\).

Method — Giving Change by Counting Up
The seller starts at the price and counts up to the money given:
  1. Start at the price.
  2. Add coins or bills one by one, without going past the money given, and say the new total each time, until you reach the money given.
  3. The money you added is the change.
It is like solving a subtraction by an addition.
Skills to practice
  • Checking If You Have Enough Money
  • Comparing Coins and Value
  • Calculating Change When Buying Items
III Going further
Skills to practice
  • Completing Equalities with Money
  • Solving Problems with Several Questions
  • Quiz