BigNumber doesn't support decimals.

[JotaStar]

BUG?

I'm trying to divide a BigNumber where the divisor is bigger than dividend, getting result 0x00.

CODE:

    // Get Reserves Of Pair
    const reserves = await pair.getReserves();
    console.dir(reserves);
    console.log(`${reserves[0].toString()} - ${reserves[1].toString()}`);

    const valoration = reserves[0].div(reserves[1]);
    const revValoration = reserves[1].div(reserves[0]);

    console.dir(valoration);
    console.dir(revValoration);
    console.log(`${valoration.toString()} - ${revValoration.toString()}`);

In this snippet I'm getting the reserves of a pair of tokens of Uniswap

67512548227127836337390183 wei => 67512548,227127836337390183 ethers
15006858949770871383 wei => 15,006858949770871383

So, valoration, (dividend is bigger than divisor), the result is as expected: 4498779.
But the reverse valoration (revValoration) should be 0.0000002221809196121586 but it's 0x00

ALL OUTPUT

[
  BigNumber { _hex: '0x37d85692a93211088e4267', _isBigNumber: true },
  BigNumber { _hex: '0xd04312b47f7c0257', _isBigNumber: true },
  1628956121,
  reserve0: BigNumber { _hex: '0x37d85692a93211088e4267', _isBigNumber: true },
  reserve1: BigNumber { _hex: '0xd04312b47f7c0257', _isBigNumber: true },
  blockTimestampLast: 1628956121
]
67512548227127836337390183 - 15006858949770871383
BigNumber { _hex: '0x44a55b', _isBigNumber: true }
BigNumber { _hex: '0x00', _isBigNumber: true }
4498779 - 0

ENV:
ethers v5.4.4

[ricmoo]

BigNumber is standard integer math. No decimals. You probably want to use the ethers.FixedNumber.

[PaulRBerg]

As Richard explained, you can't use the vanilla BigNumber for this. You can either use FixedNumber, or an external library like mathjs. If you opt-in for the latter, here's how I am using it in PRBMath:

https://github.com/hifi-finance/prb-math/blob/2534b420e3b6bc4d8d82ac0becfef0cbf6582136/helpers/math.ts