Multiplying by 10-Counting Zeroes-Beginner-Lesson 2

Multiplying by 10-Counting Zeroes-Beginner-Lesson 2

by Ann Hartter

Fact Families

Fact families work in Addition & Subtraction as well as Multiplication & Division

division is the decreasing operation for multiplication

Here's a fact family with 10

Read it out loud

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​I really like the way fact families sound out loud. It's a nice rhythm. Do you think so too?

If multiplying by 10 means you put a 0 at the end...

​Then dividing by 10 should mean taking a zero off the end?

Yes? Did this work?

​Is that correct?

​How about with larger numbers than 10?

​Yes, that looks like it works, too

​Test it with huge numbers:

I counted 9 zeroes.

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​I think it still works.

​Maybe not all the zeroes this time?

​Put three zeroes on the end to multiply

Take three zeroes off the end to divide

​Bonus: Percents!

Percent is a type of dividing by 100 AND multiplying (by any number).

Both operations happen! It's a two-part process in one symbol!

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The word PERCENT means for each 100

​​so if you see 2% that is 2 for each 100

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​Say you have 100 M&Ms. ​If you eat 2, you have eaten 2%.

That's 2 for the 100 you have.

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​Bonus: Percents!

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If you have 1000 M&Ms, to eat 2%, you will have to eat...

​well first you have to know how many hundreds 1000 is.

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​Now you need to eat 2 ten times. Wait...

that sounds familiar:

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​So you need to eat 20 M&Ms to have eaten 2% of 1000.