### Video Transcript

16088 plus 22312 plus 40792 equals what?

There are three five-digit numbers in this number sentence. And we need to add them together to find the total. Now if we have a quick glance at the numbers, we can see that this isn’t going to be the sort of calculation that we can do on our heads quickly. We’re gonna have to write it down and work it out by using pencil and paper.

Now when we add together numbers with lots of digits, we usually start with the ones, then add the tens, the hundreds, and so on. So do you think we need to start now and add together the ones: eight, two, and two? At the moment, the way our number sentence had been written is not very helpful. If we want to add together the ones, it’ll be much more helpful if all the ones were on top of each other in the same column.

So the first thing we can do to help ourselves is to set out the numbers vertically in a column edition: 16088 plus 22312 plus 40792. The way that we’ve written the calculation, we’re going to add all three numbers at the same time.

A slightly different method we could’ve used is to add the first two numbers first and then add the last number to their total. But there are a few nice pairs of digits that we could use to help us if we add all three numbers at the same time. So we’ll use the first method.

So we start by adding the ones. As we said before, eight plus two plus two. Now because we’re adding three digits at once, we could look for pairs of digits to help us add these three digits quickly. Let’s try and identify these as we add them together. For example, we can see a quick pair in the first two digits. Eight and two are a pair that we know make 10. So if we add the remaining two, this gives us a total of 12: two ones and one ten.

Now we need to add the tens. And again, there’s a pair here that can help us add them quickly. We need to add eight, one, and nine together. We know that nine and one are a pair that make 10, plus the eight makes 18. And we’ve also exchanged one lot of 10 as well. That makes 19, nine tens, 100. Once again, by adding all three digits at the same time, there’s another pair we can use as we add the hundreds digits: zero, three, and seven. Three and seven make 10. And obviously, if we add the zero, it stays as 10. We also need to add the 100 that we’ve exchanged. So that gives us 11 hundreds, which is the same as 1100.

Let’s add the thousands, six plus two plus zero. Well, we know six plus two equals eight. If we add the zero, it remains eight. But we’ve got one that we’ve exchanged, so that takes us to nine thousands. And finally, we need to add the ten thousands, one plus two plus four. We know one plus two equals three. And if we add three and four together, we get seven, seven lots of 10,000.

So by writing this calculation out vertically, we could add each set of three digits quickly. And where we could, we look for pairs of digits that we could use to help us. 16088 plus 22312 plus 40792 is equal to 79192.