How estimating sums and rounding sums similar?

When estimating sums, it is best to round to the nearest round number. If the last place on the right is less than 5, then round down. If the last place on the right is 5 or more, then round up. For...

Numbers that end in a digit of 4 or less should be rounded DOWN to the nearest ten. Example: 24 rounded to the nearest ten would be 20 Numbers that end in a digit of 5 or more should be rounded UP to...

It means to round a number to the nearest whole number, tens, hundreds, etc.

for example, 555+325. let's say we want to round this to the nearest hundred. first you find the digit in the hundreds place, i would like to mark it. then you look to the right, you would probably...

It's the sum of 42 and 13 which is 55.