Search code examples
javascriptmathjuliadivisionsubtraction

Nodejs failed to subtract number

I tried to do this calculation with Node.js.

let x = 841251657
console.log((x*x)-x)

I got: 707704349563994000 printed.

When I use julia I get 707704350405245649 for the same calculation. And I got 7.0770435e+17 for google calculator.

Apparently, something going wrong here.
What can I do to get the correct answer?

Solution

  • The maximum safe integer is defined as Number.MAX_SAFE_INTEGER, which is (2^53) -1, which is the largest integer you can represent with double-precision floating point. 

    > console.log(Number.MAX_SAFE_INTEGER)
9007199254740991

    The number you're calculating is significantly larger than that, so precision is being lost. You can check this with Number.isSafeInteger((x*x)-x).

    For numbers this big, you should be using a BigInt library.