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Discussion on: Working with extremely large numbers in JavaScript

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peerreynders profile image
peerreynders • • Edited

What is wrong with BigInt? Available since Node.js 10.4.0 (2018) and caniuse.

console.assert((10000000000000001n + 1n).toString(), '10000000000000002');
console.assert((10000000000000002n - 1n).toString(), '10000000000000001');
console.assert((10000000000000002n * BigInt(3)).toString(), '30000000000000006');
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ssadek1976 profile image
ssadek1976 •

When I tried to compute the below it gives me two different "k" constant values when they should be identical. See below results.
I´ve also tried all bignumber libraries with the exact two differing results each time.

    // transaction
const tx0 = 2755738843649989653057n; // amount0Out BMON
const tx1 = 113747760332474227520n; // amount1In BUSD

// reserve after transaction
const x = 466822693713887341798087n; // reserve0 BMON
const y = 19334468154310748213608n; // reserve1 BUSD

// BigInt method
console.log("BigInt method...");
const k = x * y;
console.log("xy ", k); // 9025768505320715115682091222146517245881767896n

const newX = x + tx0;
const newY = y - tx1;
const newK = newX * newY;
console.log("xy ", newK); // 9025635755231009297480820885627169090307684672n
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Any ideas on how to resolve this issue in JavaScript would be greatly appreciated!