# Maths

When you are rounding numbers, your would round 3.5 as 4 yet when you have to use upper bounds of a number, say 8, it would be 8.5 which doesn't round to 8. I get that it would be plus or minus o.5 as the lower bound is 7.5 but please could someone explain and help me understand why?
I think you are mixing up two concepts, when you are rounding you are actually making an approximation of the value. upper bounds are about the accuracy and errors of data( the possible range of the actual value could be).
(edited 1 month ago)
Original post by kkkk124
I think you are mixing up two concepts, when you are rounding you are actually making an approximation of the value. upper bounds are about the accuracy and errors of data( the possible range of the actual value could be).

Thank you! I think Sparx Maths' terminology just confused me
Original post by BaconBacon
Thank you! I think Sparx Maths' terminology just confused me

The numbers which round to 8 would be in the interval
7.5 <= x < 8.5
and similarly the numbers which round to 9 would be in the interval
8.5 <= x < 9.5
etc ...

For the numbers rounding to 8, the upper bound must be 8.5 as 8.49 would round to 8, so would 8.499 and 8.4999 and ... So even though 8.5 doesnt round to 8, its the least upper bound. You cant pick a smaller upper bound.
(edited 1 month ago)