Before learning how to solve coin problems, let's review what you've learned so far about multiplication number families.
You've learned that each multiplication family has two lesser (smaller) numbers that are multiplied together to equal the greatest (larger) number or product (answer).
Look at this number family.
Here, the lesser numbers are 5 and 6. The greatest number is 30. The family tells that if you multiply 5 times 6, it equals 30. If you multiply 6 times 5, it also equals 30.
The number family also tells you four facts: two multiplication facts and two division facts.
Let's start with the two multiplication facts. What's the multiplication fact that starts with the first lesser number? The first lesser number is 5. So it's 5 times 6 equals 30 (5 × 6 = 30). How about the multiplication fact that starts with the other lesser number? It's 6 times 5 equals 30 (6 × 5 = 30).
Notice that they have the same product. So if you know the answer to one, you'll know the answer to the other!
You can now use the multiplication facts to find the two division facts. These are 30 divided by 5 equals 6 (30 ÷ 5 = 6) and 30 divided by 6 equals 5 (30 ÷ 6 = 5).
Write the fact family for 5, 6, and 30:
