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## 2nd grade

### Course: 2nd grade > Unit 1

Lesson 4: Add and subtract within 20- Adding within 20 using place value blocks
- Adding within 20 using ten frames
- Subtract within 20 using place value blocks
- Subtract within 20 using a number line
- Add & subtract within 20
- Addition and subtraction word problems: gorillas
- Addition and subtraction word problems: superheroes
- Add and subtract within 20 word problems

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# Adding within 20 using place value blocks

Sal adds 8 + 6 using place value blocks. Created by Sal Khan.

## Want to join the conversation?

- Can I add within 40?(6 votes)
- what is 177+345(4 votes)
- 522, you could also write it as 500 + 20 + 2, or in word form, five hundred and twenty-two.(2 votes)

- Whats 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000×55566778900099998771122345667889000987665443221+12234567890877665443×0(4 votes)
- The answer is not 0 because of order of operations. The answer is actually 55,566,778,900,099,998,771,122,345,667,889,000,987,665,443,221,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000.(3 votes)

- what's 100,0000000000+100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000(3 votes)
- 2000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000? uh(3 votes)

- 10+40+n=100

10+40+50

n+50=100

n=100(3 votes)- You are wrong, MayaD. N is actually equal to 50. We do inverse operations. 100-50=50 It's actually easy(2 votes)

- What if you don't know your multiples?(3 votes)
- um just practice the multiplication table. 4 years ago, in 2nd grade, I wasn't good at multiplication. So I memorized it over the break. :) Hope this helps.(1 vote)

- 10+90=100x10=1000-10-90=900(3 votes)
- how do you find the integral of 2x^2-5x?(2 votes)
- ($ = integral sign)

$ 2x^2-5x = 2/3x^3 + 5/2x^2 + c(1 vote)

## Video transcript

- [Instructor] What we
wanna do in this video is think about what is
equal to eight plus six, and to help us out, we have eight blocks
shown right over here, and we have another six blocks
shown in this pink color. So pause this video and see
if you could figure it out. So there's a lot of ways to approach it, but one way that I like to do it is, let me see if I can make a group of 10 out of some of these blocks and then see how many
of them are left over. So if I want to make a group of 10, I would use all of these eight. So one, two, three, four, five, six, seven, eight, and
then I would need two more and I could get those two
more from this six here, and then I would have one,
two, three, four left over. And to see what that looks like, you can see that we could
take all of the eight and then two of the six
to make a group of 10, and so I set that up as a whole bar. So we know that our answer
is going to have one 10. So this tells us that that is, let me write it this way, one 10 and then how many ones? Well, we could see that right over here. We have four ones left over. So that is four ones. So if we think about place value, that's one 10 and four ones or 14. We have 10 and another four,
which is the same thing as 14.