" why do you think we round up when a 5 is the next digit to the right of the place in witch we are rounding ? "

i'm guessing it has something to do with numbers starting out at zero ?

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- Oct 18th 2010, 09:45 AMArchitecturalEngineerquestion i can't figure out
" why do you think we round up when a 5 is the next digit to the right of the place in witch we are rounding ? "

i'm guessing it has something to do with numbers starting out at zero ? - Oct 18th 2010, 10:04 AMNOX Andrew
0.5 is the same as one-half. If you are walking home from school and you are one-half of the distance to your home when it starts to rain, would you keep going home or turn around and head back to school?

- Oct 18th 2010, 10:12 AMArchitecturalEngineer
i still don't understand the reason for rounding up when its at 5, infact i don't understand the reasoning for rounding at all since if you didn't round you would have a more accurate number i would think...

- Oct 18th 2010, 10:18 AMUnknown008
Do you think it would be reasonable to give everytime all the numbers in pi for example?

One other thing... when you take a reading, you always take it to the nearest reading you can measure. If the exact length of something was 1.0652 cm, you will only be able to measure a length of 1 cm with a common ruler.

Rounding off is a means to simplify numbers and remove unnecessary details. This eases work. Where some accuracy is required, then you don't round off. - Oct 18th 2010, 10:42 AMArchitecturalEngineer
- Oct 18th 2010, 10:43 AMwonderboy1953
I think it's just convention.

- Oct 18th 2010, 11:03 AMSoroban

Here;s my justification.

When rounding a number, the critical digit can be any of ten digits:

. . . $\displaystyle \{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9\}$

It seems "fair" that half of them round-down and the other half round-up.

. . . $\displaystyle \underbrace{0,\:1,\:2,\:3,\:4,}_{\text{round down}}\:\underbrace{5,\:6,\:7,\:8,\:9}_{\text{roun d up}} $