Mental Math R 5-1

Multiplying with Multiples of 10
Listen to the wizard explain how to do number one.


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I'll walk you through number two.
5x3
That shouldn't take you very long, it's an easy one!
15
:)

5x30
If we see a zero like that, we can ignore it for now, and just add it to the back of the answer at the end.
If we ignore the zero, we are left with 5x3, which we just did and found out was 15.
When we put the zero on the end we have an answer of 150.

500x300
Lots of zeros here! Four to be exact. If we ignore all four of them, we have to remember to add four to the end of the answer.
We again are left with 5x3, which is still 15.
But when we add the four zeros onto the end we get an answer of 150,000.