What is the greatest number to be round off 320 and 220?

Answer 1

Without being given to the nearest, I will assume you want the greatest number that could possibly be rounded in each case:

320: to the nearest 320, any number greater than or equal to 320/2 = 160, and less than 320 + 320/2 = 480 will round to 320. Thus the greatest whole number that rounds to 320 is 479.

220: to the nearest 220, any number greater than or equal to 110, and less than 330 will round to 220. Thus the greatest whole number that rounds to 220 is 329.

If decimals are considered, there is no exact answer to the greatest number in each case other than by saying they are less than 480 and 330 respectively.

eg the greatest number to round to 320: 479.9 is close, 479.9999 is closer, 479.99999999999 is closer still, but an extra digit 9 can always be appended on to the end of any (decimal) number specified to make a bigger number that also rounds to 320.