Question

how can we round off or round up if
105 nearest 10
210 nearest to 100
the next thing is that if we have at the end 6even number and then shouldn't we round it up e.g 64.6 can we round it or not?

Answer 1

if the number after the place you have to round to is 5 or higher then you round the previous number up.
if it is 4 or lower the previous number stays the same.

Answer 2

in your example 105, if you are rounding to the tens place then it would indeed be 110.
you are rounding to the tens place, there is a 0 there, the nect number is 5 or greater so the 0 turns into a 1.

Answer 3

16.66 can't be round up but i saw in some question it becomes 16.7 but it not right ?
and 210 change into what we want to round it nearest 100