Step 44: Multiplication – 2, 4, 8, 5, 10
Good framework
These numbers are usually quick to learn, and once learned they provide a good framework for learning the remaining numbers.
Multiplying by 5 and 10
Knowing how to multiply by 10 is quick to learn, and it is important for understanding place value. It also can make it easier to learn how to multiply by 5.
The 5’s can either be learned by skip counting by 5 until they become automatic, or they can be learned using the 10’s. If you multiply 6 times 5, that will give you half as many 10’s. Half of 6 is 3, so the answer is 30. If you multiply 7 times 5, you need to put one of the 5’s off to the side and proceed as you would for 6 times 5. The answer for 6 times 5 is 30, and then adding in the 5 held in reserve gives the answer of 35.
Multiplying by 2, 4, and 8
These three can be done with lots of doubling. Your child should have had lots of practice with doubling and multiplying by 2. Multiply by 4 either by skip counting or by doubling the answer from multiplying by 2. For example 4 times 3 is twice as much as 2 x 3, so the answer is 6 doubled, which is 12. Multiply by 8 by skip counting by 8 or by doubling the answer from multiplying by 4.