Javascript's Modulus broken?

Asked Oct 17 '16 at 14:40

Active Oct 17 '16 at 14:45

Viewed 34 times

I just found out that when you type Math.pow(5,25) % 5 in the console, it returns 2. This also happens when you first solve Math.pow(5,25) (298023223876953150 % 5 = 2). But that number is clearly divisible by 5, because it is a power of 5...

Has anyone an idea what is going on here?

(I also saw that the outcome of Math.pow(5,25) is wrong, it is 25 higher than the real number, does someone knows how this works too?)

asked Oct 17 '16 at 14:40

user3722860

5

It's because the genuine result of `Math.pow(5, 25)` is well into the region where not all integers can be accurately represented by IEEE-754 double-precision floating point numbers, so it gets rounded to the nearest one (`298023223876953150` ), which is a different number. There's a duplicate here somewhere... – T.J. Crowder Oct 17 '16 at 14:41
1

@T.J.Crowder I saw. I realised. I removed. I stoopid. – evolutionxbox Oct 17 '16 at 14:43
@evolutionxbox: LOL We've all done it. – T.J. Crowder Oct 17 '16 at 14:44
it was not evolutionxbox but me, I removed my comment – n00dl3 Oct 17 '16 at 14:50
`(298023223876953150 > Number.MAX_SAFE_INTEGER) === true` – evolutionxbox Oct 17 '16 at 15:04

Javascript's Modulus broken?

0 Answers0