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Lesson 4: Multiplying by tens

# Multiplying by multiples of 10

Sal decomposes multiples of ten to multiply. Created by Sal Khan.

## Want to join the conversation?

• why cant we just multiply 5x7 then add a 0 to the end?
• for 50x7? You can. He's just explaining the underlying process here. With enough practice, you will be able to easily shift 0's around given a certain power of 10.
• why didn't you just multiply the thing then just working it out the long long long way!?
• Well, he is just doing this because it is gonna give you a better comprehension if he does a harder problem. I mean, if he did 1*7 (1x7 or 1 times 7), you would not learn anything because you already know the answer, and it won´t help you at all.
• keyanna is right why can`t we do that
• i put this all on my note book thank khan
• Hi are you
Pi=3.1415926
• why cant we just multiply 5x7 then add a 0 to the end?
• you can but he does it so it will be clear to the watchers (what I mean is that it is people watching)
• All you had to do was multiply 50 x 7 right? You see the number 5 and 7 and you'll think that oh! I think we need to multiply 5 x 7 and get the answer of 35! And then i will add my zero in and get my answer of "350".
See? Ez math.