Video Transcript
Use a number line to find 78 take
away 45.
We need to find the answer to a
subtraction here, 78 take away 45. And on the number line, we can
already see the number 78 is marked on there for us. Now, if we’re going to take away
45, we need to count backwards. Now, we could count back in ones 45
times, but that’s gonna take us quite a long time. Instead, let’s break up the number
45 into 10s and ones, and then we can count back in 10s and then ones. 45 is the same as 40 plus five.
We know that 40 is the same as four
10s and five is equal to five ones. So, if we’re going to take away 45,
we need to make four jumps of 10 and then five jumps of one. Let’s begin by counting back four
jumps of 10. We’ll start with the number 78. 78, 68, 58, 48, 38. We’ve counted back four 10s and
we’ve gone from 78 to 38. Now, we just need to take away five
ones. So, we need to make five jumps of
one, and we’ll start counting back from the number 38. 37, 36, 35, 34, 33.
We started with the number 78. And because we had to take away 45,
we jump back four 10s and then five ones because four 10s and five ones are the same
as 45. But by skip counting in 10s for
some of the subtraction, it speeds things up a bit. The number we ended on was 33. So, we can say 78 take away 45
equals 33.
