When you buy low-priced items or fill your piggy bank, you want to know how much the coins are worth. It's important to know how to match a penny, nickel, quarter, or dime to an amount. Coins are very useful when learning about multiplication and division problems.
We will practice what you've learned about using coins to make multiplication and division number families. You've learned that you add, subtract, and multiply when you divide. You can better see how these math operations work together when you use coin number families.
Let's start with a coin problem with dimes. Do you still remember how they work?
If you know how much each coin is worth, you know the first lesser number (smaller number) in the family. What's the lesser number? It's 10 because each dime is worth 10 cents.
What's the other lesser number? This tells how many dimes you have. It's D. You have 5 Ds. What's the greater number (larger number)? This is the number of cents you have. You have 10 times 5 (10 × 5). The answer equals 50 cents.
Now let's solve a similar problem that tells how many coins you have. Let's use nickels.
A nickel is worth 5 cents, so 5 is the first lesser number in the family. You have 5 nickels, so 5 is the other lesser number. Multiplying 5 by 5 gives you 25 (5 × 5 = 25). The number of cents you have, 25, is your greater number. You have 25 cents.
Here's a coin problem that tells how many cents you have:
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A quarter is worth 25 cents. Write 25 for the first lesser number. The greater number is the total number of cents, so write 75. To figure out the number of quarters, divide the number of cents by how many cents each quarter is worth. So 75 divided by 25 equals 3 (75 ÷ 25 = 3). You have 3 quarters!
