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javascriptdecimaldecimal.js

decimaljs add method work incorrectly for big number

I'm using the Add method of decimalJS v10.4.3 to add 2 numbers: 12345678907812569090001 and 5001.

The result should be 12345678907812569095002 but decimalJS returns 12345678907812569095000

Any suggestions?

Solution

  • It must be because precision is less than the number of digits, so it ends with ...00

    var a = new Decimal("12345678907812569090001")
var b = new Decimal("5001")
var c = a.add(b)
console.log (c.toFixed())
    <script src="https://cdnjs.cloudflare.com/ajax/libs/decimal.js/9.0.0/decimal.min.js" integrity="sha512-zPQm8HS4Phjo9pUbbk+HPH3rSWu5H03NFvBpPf6D9EU2xasj0ZxhYAc/lvv/HVDWMSE1Autj19i6nZOfiVQbFQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

    However should we set precision to a large enough number, it works: default is Decimal.precision = 20

    Decimal.precision = 100

var a = new Decimal("12345678907812569090001")
var b = new Decimal("5001")
var c = a.add(b)
console.log(c.toFixed())
    <script src="https://cdnjs.cloudflare.com/ajax/libs/decimal.js/9.0.0/decimal.min.js" integrity="sha512-zPQm8HS4Phjo9pUbbk+HPH3rSWu5H03NFvBpPf6D9EU2xasj0ZxhYAc/lvv/HVDWMSE1Autj19i6nZOfiVQbFQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>