Solidity – Understanding the Logic Behind Q64.96 Number

bignumberethereumjssolidityuniswap

Checking the math behind uniswap v3 and I constantly seeing the term: Q64.96 in sqrtRatioX96

I am just wondering if this is a naming convention in smart contract world to describe the format of the number? if so, what does it exactly mean? (Not asking the pricing logic behind Uniswap v3)

https://docs.uniswap.org/protocol/reference/core/libraries/SqrtPriceMath

Best Answer

This looks like a notation in math: https://en.wikipedia.org/wiki/Q_(number_format)

For example, the specification Q3.12 describes a signed binary fixed-point number with a w = 16 bits in total, comprising the sign bit, three bits for the integer part, and 12 bits that are assumed to be fraction. That is, a 16-bit signed (two's complement) integer, that is implicitly multiplied by the scaling factor 2−12

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[Ethereum] Truffle CMD Bignumber to number; hex to string

Contract function calls in Truffle return promises so you have to add a callback to get the response. If getAge() is declared as either constant, pure or view in the Solidity contract you can do instance.getAge().then(age => age.toNumber()) if it doesn't have any of those modifiers then you need to do instance.getAge.call().then(age => age.toNumber())

Solidity JavaScript – How to Convert Big Number to Normal Number?

It depends what you mean by real number. You can check out here the divisions used in Ethereum.

For wei:

let bigNo = await this.crowdsale.rate();
console.log(bigNo.toNumber());

For ether add this:

console.log(web3.fromWei(bigNo.toNumber()));

If you're using version ^1.0.0 of web3, use web3.utils.fromWei instead of web3.fromWei.

Best Answer

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[Ethereum] Truffle CMD Bignumber to number; hex to string

Solidity JavaScript – How to Convert Big Number to Normal Number?

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