Simple Purchasing & Change Problems - First Grade Mathematics

Money becomes truly exciting when you use it at a store to buy things you enjoy! Whether you are picking out a delicious red apple at a grocery stand, buying a shiny sticker at a school fair, or paying for a small toy, money story problems are real-life math in action. When you buy something, you need to know two things: "Do I have enough money to pay?" and "Will I get any change back?" In this chapter, you will master solving purchasing stories and finding change within 20 cents.

Purchasing: Adding Prices Together

When you buy more than one item, you must join their costs together using addition to find the total price.

The School Fair Purchase:
Item 1: A superhero sticker costs 8¢.
Item 2: A bookmark costs 6¢.
What is the total cost for both items?

Math Model:
Sticker:  [ 8¢ ]
Bookmark: [ 6¢ ]
Equation: 8¢ + 6¢ = 14¢
Total Cost: 14¢!

Checking Your Pockets

If you have 15¢ in your pocket and the items cost 14¢, do you have enough? YES! Because 15¢ is greater than 14¢ (15 > 14), you have enough money to make the purchase!

Making Change: Subtracting the Price from What You Paid

What happens when you pay with a coin that is worth more than the item's price? The shopkeeper gives you back the extra money! That extra money is called change.

Finding Your Change:
Story: A carton of milk costs 7¢.
You hand the cashier a DIME (10¢).
How much change will you get back?

The Change Equation:
[ AMOUNT PAID ]  -  [ COST OF ITEM ]  =  [ CHANGE BACK ]
      10¢        -         7¢         =        3¢

Answer: You receive 3¢ in change!

The Logic of Change

You gave the cashier 10¢. The cashier only needed 7¢. So the cashier subtracts the 7¢ price and returns the remaining 3¢ to your hand.

Example with a Nickel and Dime

Let us practice another change problem.

The Story:
Leo buys a shiny red pencil for 12¢.
He pays with two dimes (20¢).
How much change does Leo receive?

Step 1: Calculate amount paid: 2 Dimes = 10¢ + 10¢ = 20¢.
Step 2: Subtract the cost: 20¢ - 12¢ = 8¢.
Answer: Leo gets 8¢ in change!

Practice Exercises

Exercise 1: Sophia wants to buy an apple that costs 9¢ and a banana that costs 8¢. How much money does she need in all? Write the addition equation with the cent symbol.

Exercise 2: Marcus has 15¢. He buys a toy whistle for 11¢. How much money does Marcus have left? Write the subtraction equation.

Exercise 3: A postcard costs 6¢. You pay the cashier with a dime (10¢). How much change should the cashier give back to you?

Exercise 4: Explain what the word "change" means in a money transaction.

Solutions and Explanations

Solution to Exercise 1: 9¢ + 8¢ = 17¢. Sophia needs 17¢ in all.

Solution to Exercise 2: Marcus started with 15¢ and spent 11¢: 15¢ - 11¢ = 4¢. Marcus has 4¢ left.

Solution to Exercise 3: A dime is worth 10¢. Subtract the 6¢ cost: 10¢ - 6¢ = 4¢. The cashier should give you 4¢ in change.

Solution to Exercise 4: "Change" is the extra money returned to a buyer when they pay with a coin or bill that is worth more than the cost of the item being purchased. It is calculated by subtracting the item's price from the amount paid.