Primary 3 Money
Align the decimal points when adding or subtracting money. To calculate change, subtract the total cost from the amount paid.
Keywords
- Dollar
- The main unit of money; $1 is 100 cents.
- Cent
- One hundredth of a dollar.
- Decimal point
- The point separating dollars from cents.
- Total cost
- The prices added together.
- Change
- The amount paid minus the total cost.
Add and subtract money
Align the decimal points so digits of the same place value are in the same column. Write each amount with two decimal places.
Line up dollars and cents
$12.35 + $6.40 = ?
| Dollars | Point | Cents | |||
|---|---|---|---|---|---|
| Tens | Ones | . | Tens | Ones | |
| First | 1 | 2 | . | 3 | 5 |
| + | 6 | . | 4 | 0 | |
| Answer | . | ||||
Keep the decimal points in one column.
See worked example
Work out $12.35 + $6.40.
- Place $12.35 above $6.40 with the decimal points aligned.
- Add the cents: 35¢ + 40¢ = 75¢.
- Add the dollars: $12 + $6 = $18.
Answer: $18.75.
Try together
Work out $18.75 − $6.40.
Reveal the answer
$12.35. Subtract 40¢ from 75¢ and $6 from $18.
Find the change
Add the prices to find the total cost. Subtract the total cost from the amount paid to find the change.
Maya buys a notebook for $6.45 and a pen for $2.30. She pays $10.00. How much change does she get?
Step 1: Find the total cost
The notebook and pen are two parts. The total cost is unknown.
Total cost: $6.45 + $2.30 = $8.75
Step 2: Find the change
The $10.00 paid is the whole. The cost and change are its two parts.
Change: $10.00 − $8.75 = $1.25
Maya gets $1.25 change.
See worked example
Maya buys a notebook for $6.45 and a pen for $2.30. She pays $10.00. How much change does she get?
- Total cost: $6.45 + $2.30 = $8.75.
- Change: $10.00 − $8.75 = $1.25.
Answer: $1.25.
Try together
A pencil costs $2.40. Ben pays $5.00. How much change does he get?
Reveal the answer
$5.00 − $2.40 = $2.60.