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## 3rd grade (Eureka Math/EngageNY)

### Unit 3: Lesson 5

Topic E: Analysis of patterns and problem solving including units of 0 and 1- Identity property of 1
- Multiply by 0 or 1
- Divide by 1
- Divide by 10
- Represent multiplication on the number line
- Patterns with multiplying even and odd numbers
- Patterns in multiplication tables
- Patterns in multiplication tables
- Relate multiplication and division equations
- Fact families
- Find missing factors (1-digit multiplication)
- Multiplication and division word problems (within 100)
- 2-step estimation word problems
- 2-step word problem: running
- Represent 2-step word problems with equations
- 2-step word problems
- Use associative property to multiply 2-digit numbers by 1-digit

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# Identity property of 1

The identity property of 1 says that any number multiplied by 1 keeps its identity. In other words, any number multiplied by 1 stays the same. The reason the number stays the same is because multiplying by 1 means we have 1 copy of the number. For example, 32x1=32. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

- How would you solve 2888 x __ = 1?(29 votes)
- how do you get the same number in multiplication but not in addition so basically 1 is like plus 0 in multiplication?(15 votes)
- Multiplying by one is like saying "I have one set of this" so, in a way, yes, you're right, but it isn't a very good idea to think like that, because it will cause you to get confused later on.(2 votes)

- why are questions less and videos more. i didnt like it(5 votes)
- Yeah. I don't like it too. Maybe there is more videos to prepare you more to your path to mastery.(5 votes)

- Why does he sometimes use the dot for the multiplication symbol?(4 votes)
- The reason why he uses the dot, is because of algebra. Once you get into algebra you stop using an x for multiplication, because it gets confusing when you have variables, which you do most of the time in algebra. The most common letter to use as a variable is an x, so 8xx is very confusing.(4 votes)

- What does it do(2 votes)
- The identity property of 1 is trying to tell you that
**any**number multiplied with 1 retains its identity. In other words, its value does not change.

Hope this helps.(5 votes)

- Feels like Sal is teaching us multiplication?(2 votes)
- The identity property of 1 is based on what happens when you multiply with 1. It basically is trying to show you that any number multiplied by 1 will = the original number (its identity is not changed).(5 votes)

- what happens if it is 56'2(3 votes)
- 56 times 2 = (50+6) times 2 = (50 times 2) + (6 times 2) = (100) + (12) = 112;

something times 2 is double the something, like 4*2 = 8;

"double it" should not be confused with "doublet." ;)(3 votes)

- Why does he makes this so complicated I am switching curriculums next year ugh(3 votes)
- If you multiply a value by -1, would it still be considered the Identity Property of Multiplication?(2 votes)
- No because it changes the value of the number(3 votes)

- how is it that the dot is a other way for mulitiplcation.(2 votes)
- Because when you have parentheses it will look like you are doing the variable "x". Doing a dot will assure that you are multiplying.(3 votes)

## Video transcript

We're asked to multiply
65 times 1. So literally, we just need to
multiply 65-- we could write it is a times sign like that or
we could write it as a dot like that-- but this
means 65 times 1. And there's two ways
to interpret this. You could view this as the
number 65 one time or you could view this as the
number 1 sixty-five times, all added up. But either way, if you have one
65, this is literally just going to be 65. Anything times 1 is going
to be that anything, whatever this is. Whatever this is times
1 is going to be that same thing again. If I have just some kind of
placeholder here times 1, and I could even write it as the
times symbol times 1, that's going to be that same
placeholder. So if I have 3 times 1,
I'm going to get 3. If I have 5 times 1, I'm going
to get 5, because literally, all this is saying
is 5 one time. If I put-- I don't know-- 157
times 1, that'll be 157. I think you get the idea.