How to Multiply by 1

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  • 0:02 Multiplication by 1
  • 1:41 The Rule
  • 2:07 Examples
  • 2:47 Lesson Summary
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Lesson Transcript
Instructor: Yuanxin (Amy) Yang Alcocer

Amy has a master's degree in secondary education and has taught math at a public charter high school.

After watching this video lesson, you will know how to multiply any number by 1. You will know what the rule is for multiplying by 1, and you will know how easy it is to find the answer to any multiplication by 1 problem.

Multiplication by 1

Multiplication means repeated addition. When you have a multiplication problem, it is telling you how many times to add a certain number. For example, 3 * 8 (three times, or multiplied by, eight) means you are taking the 3 and adding it eight times. 3 * 8 = 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3. When you are multiplying, it doesn't matter which order your numbers are in. 3 * 8 is the same as 8 * 3. Multiplication also tells you how many groups you have of a certain number. 3 * 8 means you have 8 groups of the 3. Do you see that?

In this lesson, we are talking about multiplication, but specifically about multiplication by 1. What does it mean to multiply something by 1? If we view our multiplication as telling us how many groups of something we have, then multiplication by 1 means we have just one group. So, 38 * 1 means we have one group of 38. Can you figure out what 38 * 1 equals? That's right, it equals 38 because we have just one group of 38. We don't have more or less, just one group of 38. What about 431 * 1? What do you think that equals? Did you say 431? If you did, then you are right! Give yourself a pat on the back!

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