Video Transcript
Find the following: 236 plus
148.
Did you know in this question we’ve
already been given a hint to help us? Perhaps you find it difficult to
recognize. But if the calculation had been
written like this, we might have found it trickier to work out. The way that our calculation has
been written, with the ones, the tens, and the hundreds digits in neat separate
columns, gives us a bit of a clue. Perhaps we need to add each column
separately.
Now, we always start by adding the
ones digits first, and we’ll explain why in a moment. Six ones plus eight ones makes a
total of 14 ones. Now, we know we can only write a
one-digit number in the ones place. So how can we represent the number
14? We can take 10 of our ones and
exchange them for one ten. And we write that little one ten in
the tens place. This is just to remind us when it
comes to adding the tens, we need to include this extra ten. So 14 is now one ten and four
ones. Can you see how this is still the
same as 14 ones? We’ve just regrouped the
number. It’s important to remember that
when we regroup a number like this, it doesn’t change its value.
On to the tens. Now, when we first looked at our
calculation, we might say three tens plus four more tens equals seven tens. So surely, the answer is going to
have seven tens in it. And, you know, if we’d have started
with the hundreds digit and work from left to right, we might well have written the
digit seven in the tens place. But don’t forget we exchanged 10
ones in the number 14, and we’ve got an extra ten to think about. Good job we started by adding the
ones, isn’t it? Our answer is not gonna have seven
tens, but eight tens.
Finally, if we add the digits in
the hundreds column, 200 plus another 100 equals three hundreds altogether. We’ve used column addition to add
these two three-digit numbers together. We even regrouped some ones where
we needed to. We exchanged 10 ones for one
ten. And so we’ve worked out that 236
plus 148 equals 384.
