Video Transcript
Use place value to add numbers. Pick the correct way to break apart
37 into tens and ones. Add 40 to 37 by adding four
10s.
The main calculation that we need
to do in this question comes right at the end. We need to add 40 to 37. But before we get to the answer,
there’s one or two things we need to do. Our third sentence tells us that
this question is all about using place value to add numbers. Do you remember what place value
means? It’s all about the way that the
digits in a number have different values depending on where you write them, isn’t
it? And we can see just by quickly
looking through this question, we’re thinking about two-digit numbers.
The first thing we need to do in
our question is to pick the correct way to break apart 37 into tens and ones. We know from later on that 37 is
one of the numbers that we’re going to be adding, and it seems that it’s going to be
helpful to us to split it up into its tens and its ones. We’re shown four different place
value grids, and each one shows a different number of tens and ones, but which one
is correct? Seven 10s and three ones; seven
10s, zero ones; three 10s, seven ones; or three 10s, zero ones.
To help us, we could think about
what might happen if we put the digits in 37 into a place value table. If we were doing this, we’d write
the three in the tens column and the seven in the ones column. In other words, we could model 37
out of base 10 blocks by using three 10s blocks and seven ones blocks. And this will help us identify the
correct answer. Can you see it? It’s this place value table, isn’t
it? It contains three 10s and seven
ones.
In the final part of the question,
we’re told then to add 40 to 37 by adding four 10s. The numbers that we need to add
together, which are 37 and 40, have been written in a place value table. Now the calculation could have been
written like this, but by writing the digits in a place value table, we’re really
doing what we’ve done in the first part of the question. We’re splitting them up into their
tens and their ones.
Can you see that both the tens
digits are above each other and both the ones digits are above each other, too? Now, we’re told we need to add 40
to 37 by adding four 10s. This is because 40 is worth four
10s. If we look at it in our place value
table, can you see that there’s a four in the tens place and there aren’t any ones
to add at all? 40 is just worth four 10s. 10, 20, 30, 40.
So our starting number has three
10s and seven ones, and we need to add to it four 10s. If we start by thinking about the
ones, we know that we’re not adding any ones. 40 is just four 10s. So we started off with seven ones,
and we’re going to end with seven ones. Seven plus zero equals seven, but
our tens digit is going to change. 37 has three 10s, and we need to
add four more 10s. And three plus four more equals
seven. If we combine our 10s blocks,
you’ll see how our number changes.
Our answer still has seven ones,
but our tens digit has changed from three to seven. We’ve used our knowledge of place
value to add together a two-digit number and a number of tens. The correct way to break apart 37
into tens and ones is three 10s, seven ones. And to add 40 to this number, we
just needed to add four more 10s. 37 plus 40 equals 77.
