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### Course: 2nd grade > Unit 1

Lesson 2: Add using arrays# Repeated addition: haircuts

Sal solves word problems by adding the same number many times.

## Want to join the conversation?

- so 5+5+5+5+5 is the same as 5*5(16 votes)
- Yes it is. Though if you want to write it extremely short you could just say 5 squared or 5 with a superscript 2(11 votes)

- so is repeated addition like multiplication?(11 votes)
- Yes, since multiplication consists of repeatedly adding a number, therefore a multiplication allows you to abbreviate a sum, in order not to repeat the sum of the same numbers.
*I hope I have helped*...(7 votes)

- How do you know when to add objects vertically or horizontally in repeated addition?(9 votes)
- It doesn't matter. You can do either one.(3 votes)

- Wait so why would we say 2*2*2*2 = 16? That does not make sense. Why would it not be 8 because 2*4 is 8?(0 votes)
- 2*4 is not the same as 2*2*2*2.

2*4 is the same as 2+2+2+2 because multiplication is repeated**addition**.

One way to multiply 2*2*2*2 is to multiply by 2 one step at a time:

2*2*2*2 = 4*2*2 = 8*2 = 16.

Another way to multiply 2*2*2*2 is to group the two pairs of 2’s together:

2*2*2*2 = (2*2)*(2*2) = 4*4 = 16.

Have a good day!(2 votes)

## Video transcript

- [Voiceover] There are
four seasons each year. Rafael gets a haircut
two times each season. One at Arlo's barber shop, and
the other at Awesome Snips. Which choices represent the number of haircuts Rafael will get this year? And they've even made a little diagram for us right over here. So they tell us there's
four seasons in the year, Spring, Summer, Autumn, Winter. And that each season
Rafael gets two haircuts. He gets one at Arlo's
and one at Awesome Snips. So in Spring this is
the one that he gets at Arlo's, this is the one that
he gets at Awesome Snips. And Summer, this is the
one he gets at Arlos', this is the one he gets at Awesome Snips. Autumn this is the he gets at Arlo's, this is the one at Awesome Snips. And Winter, this is the one at Arlo's, this is the one at Awesome Snips. So they ask us, which choices represent the number of haircuts
Rafael will get this year? Well one way to this about it is: In Spring he will get two haircuts then in Summer he is going to
get another 2 haircuts. In Autumn he is going to
get another two haircuts. And then in Winter he is going
to get another two haircuts. So he is going to get two in Spring, plus two in Summer, plus two in Autumn, plus two in Winter. Which is going to be
equal to eight haircuts. So which of these represent eight? Well let's see, two plus
two, that's not eight. Four plus four plus four plus four, that's not eight, that's 16. Two plus two is four. Four plus four is eight, plus four is 12 plus four is 16, that's not eight. Four plus four, that is equal to eight. That is the number of haircuts Rafael is going to get this year. So we can check that one. Two plus two plus two plus two, that's exactly what we
wrote here, and it is eight. So that is equal to the number of haircuts he is going to get this year. And then two plus four, well that's not equal to eight, that's
six, so that's not right. So these are the two that represent the number of haircuts
Rafael will get this year.