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## Early math review

# Place value example: 42

Sal shows 42 as 4 tens and 2 ones.

## Want to join the conversation?

- what does < > mean(14 votes)
- < means "less than."

> means "greater than."

4 < 10; 4 is less than 10.

5 > 1; 5 is greater than 1.(15 votes)

- Is there a video for place value for decimals?(2 votes)
- I need help with this problem what is 1 ten plus 18 ones make(2 votes)
- One ten equals 10 so you just have to add that to 18 and you get 28!(1 vote)

- What about the triple digits?(2 votes)
- Triple digit numbers use hundreds, tens, and ones as place values. For example, 648 means 6 hundreds, 4 tens, and 8 ones.(0 votes)

- Do negative numbers have place value?(1 vote)
- Yes they do its similar to the one positive numbers use(2 votes)

- At3:59, what number system is Sal referring to?(1 vote)
- The decimal numeral system (also known as base 10).(1 vote)

- What is 4 tens and 19 ones? 59? What is it?(1 vote)
- Yes, you are correct. It is 59, because 4 tens means that you have 40 ones and 40 + 19 = 59.(1 vote)

- What is the standard form of 4 tens + 5 ones + 1 hundreds?(1 vote)
- It is 145, which can be broken down into 1 hundred, 4 tens and 5 ones (100 + 40 + 5 = 145). Hope it helps(1 vote)

- Why does Sal put dots on the bars at1:08?(0 votes)
- He was counting his second group of ten, he put the dots on the bars so he could keep track better. If you count the dots in each bar, there will be only 10.(1 vote)

## Video transcript

Voiceover:What I want to
do in this video is take this quantity represented
by these greenish emerald-looking bars, where
each bar represents one, and try to represent them
using the digits that we know, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. And the way I'm going
to do it is I'm going to group this into tens
so I'm going to see how many tens I have and then essentially how many ones that I have left over, so let's try to group
this into groups of ten. So 1, 2, 3, 4, 5, 6, 7, 8, 9, Let me actually, I
messed that up, let see, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. So that's one group of
ten right over there. Let me box that off so
that i know that is ten. So, that's one group
of ten, now let's see, let's see if I can get a few
more groups of ten in there. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. That's my second group
of ten right over there. Second group of ten and now let's see, it looks like I got several
more groups of ten here. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. So that's a third group of ten, and it looks like I might
be able to get one more, so that's my third group
of ten and then we have, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. So that's my fourth group of ten. Fourth group of ten right over here. So I was able to fit in
at least just this is 1, This is a ten right over here, This is another ten right over here. That's the third ten, and
then that's the fourth ten. So we can say that's 10+10+10+10. Or all of this combined is equal to 4, 1, 2, 3, 4, tens but I'm
not done with the number, I still have 1, 2, I
have 2 ones left over. So this is a one, so that's
a one right over there. And then this is another
one, so that's another one. So I have 2 ones, so this right over here, That is 2 ones, remember for each of these little green bars we
said represents a one. So this whole number is what? What's going to be the 4 tens,
1 ten, 2 ten, 3 tens, 4 tens. Plus the 2 ones, so
let me write that down. So it is 4 tens plus 2
ones, but what is that? Well if we use the number systems that we're used to
representing, we would say, "Well look, our number system gives us a way of representing that." Because the first place,
this is the ones' place So let me gets some of this blue color, So this is the ones' place. There we use one of the digits,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, To see how many ones we have. And we have 2 ones. And then the next place over to the left, that's where we say how many tens we have. That's where we say how many tens. And we know how many tens
we have, we have 4 tens. So the way that we would represent this in our number systems we would say that this was 4 tens and 2 ones. We call this right over
here, we call this 42. Another way that you can think about this, is 4 tens, that's 10+10+10+10, that's going to be 40, but once again, we're using our number
system to represent this, and then we have 2 ones but
I like to write it this way, just to remind ourselves that this 4 which represents 4 tens also represents 40. Because 4 tens is 40.