Numbers & Counting | Arithmetic | Fractions & Decimals | Prealgebra | Site Map

Bring on Some Subtraction

Let's try one example. You know about subtracting harder decimals than these, so it shouldn't be a problem. Money is like working with decimals, but easier.

Example:
Sammy needs to buy some food for lunch. He wants an apple, a banana, and a drink. Each apple costs 45 cents, each banana costs 35 cents, and a drink is 75 cents. Sammy has $2.00 in his pocket. How much change will he get after he buys his food?
Answer:
His total food cost is 0.45 + 0.35 + 0.75 = 1.55
Now we subtract the cost of the food from the money he has.
2.00 - 1.55 = 0.45
Sammy gets $0.45 (forty-five cents) in change.

Remember that even though our answer didn't have a zero in the dollar place, when you write out values for money, you always need two places to the right of the decimal point and at least a zero in the ones column. You can't write that something costs $16.7 dollars. You should write $16.70 so people understand what you mean. You should write that something costs $0.45 or just 45 cents. It is confusing to see the decimal point when you write $.45.

Example:
Todd earned $17.50 when he worked over the weekend. He went out to buy a toy that cost $5.25, some food that cost $10.65, and a new mouse for his computer that was $8.75. Did he have enough money to buy everything? How much money does he still need?
Answer:
• Start by figuring out how much everything cost.
5.25+10.65+8.75 = 24.65
• Todd only has $17, so he doesn't have enough money to buy it all.
• Use subtraction to find out how much he needs.
24.65-17.50 = 7.15

Todd needs an additional $7.15 if he wants to buy everything on his list.

Related Activities

Related Links