Video Transcript
Which of the following numbers can
be 230 when rounded to the nearest 10? 237, 224, 228, or 220.
Each of the possible answers to
this question is a three-digit number. And this question is all about
rounding numbers like these to the nearest 10. Now often, with questions like
these where we have to round numbers, we’re given a number, and then we have to
round that number to the nearest 10. But this question is slightly
different. In this question, we’re given a
multiple of 10. That’s the number 230 in our
question. And we need to find the number that
rounds to this multiple of 10. So in a way, we’re sort of working
backwards here. If we were asked to round each of
these numbers, which one would we round to 230? Well, there are only four answers
to choose from, and one of them we can cross off straightaway. Can you spot which one?
Our last answer is a multiple of 10
already; it’s 220. So we would never need to round
this number to the nearest multiple of 10. It is a multiple of 10. This leaves us with only three
possible answers. Now we know that the number 237 is
in between two multiples of 10, 230 and 240. So do you think we need to round
this number down to 230 or up to 240? Well, if we look at the ones digit
of our number, we can see it’s a seven. And we know that any number that
has a ones digit of five or more, we round up. 237 rounded to the nearest 10 is
240 not 230.
Our next three-digit number is
224. We can draw this on the same number
line, but we are going to have to extend it in one direction here because we know
224 is in between 220 and 230. And the ones digit of this number
is a four. Now, whilst any number that ends in
a five, six, seven, eight, or nine we round up, any number that ends in a four or
less we round down. And so 224 rounded to the nearest
10 is going to be 220 not 230. So this only leaves us with one
possible answer. We know that 228 is in between 220
and 230. But this time, the digit is five or
more, so we can round up. The number that we write as 230
when we round it to the nearest 10 is 228.
