乘法
const multiplyWithPrecision = (a, b) => {
const [aInt, aDecimal] = a.toString().split('.')
const [bInt, bDecimal] = b.toString().split('.')
const decimalLength = Math.max(aDecimal?.length || 0, bDecimal?.length || 0)
const product = (a * b).toFixed(decimalLength)
return parseFloat(product)
}