Greetings!
"Use division to check a multiplication problem"...
Since multiplication and division go hand in hand, when a multiplication problem is reversed, it turns into a division problem!
For Example:
3*3=9
or
9/3=3
"Use addition to check a multiplication problem"...
When you multiply a number by a number, you are essentially adding a number together a certain amount of times!
For Example:
To check whether the answer to 12*3 is actually 36, you can add the 12, three times together:
12+12+12
=36
Hope this helps.
-Benjamin