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Question

Rounding to nearest 100

Answer 1

A:

Is this homework?

Generally, mod 100, then if >50 add else subtract.

Brian 2009-02-25 06:30:58

No its not home work :-)

Senthoor 2009-02-25 06:54:41

What the hell Brian! mod and if-then-else that's gonna be really slow. If you're using integers check David's answer. It's a branch-less common way to solve this problem. It works with floating-point numbers as well.

John Leidegren 2009-02-25 06:55:15

I myself came up with this answer in Ruby. numbers.each {|number| puts number + '->' + number.gsub(/\d\d\d$/,(number[number.size-3,1].to_i + number[number.size-2,1].to_i / 5).to_s+'00')}

Senthoor 2009-02-25 07:05:51

Answer 2

+5 A:

For input n:

(n + 50) / 100 * 100

using integer division.

Note that many languages/libraries already have functions to do this.

David Zaslavsky 2009-02-25 06:31:20

Answer 3

+1 A:

This will do it, given you're using integer math:

n = (n + 50) / 100 * 100

Of course, you didn't specify the behavior of e.g., 1350 and 1450, so I've elected to round up. If you need round-to-even, that'll not work.

derobert 2009-02-25 06:32:10

Answer 4

+2 A:

100 * round(n/100.0)

Nikhil Chelliah 2009-02-25 06:35:47

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Rounding to nearest 100

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