## DEV Community # Converting big strings of number into Number

there are several ways used to convert a string to number such as

1. Number(str)
2. parseInt(str, 10)
3. (+str)
4. (str * 1) and so on.. where str is a number string like str = "123"
``````str = "123"
'123'
console.log(+str)
Output: 123

``````

However, the above ways don't work when you have a very big string

``````let str = "6145390195186705543"
console.log(Number(str))
Output: 6145390195186705000

``````

Here We get unexpected output, because we are dealing with a big string number.

Walk around:

BigInt values represent numeric values which are too large to be represented by the number primitive.

Using BigInt to convert a big string number

``````let str = "6145390195186705543"
console.log(BigInt(str))
6145390195186705543n
``````

And here we get the expected output with n appended at the end
In case you want to do some mathematical operations on your output, yeah, it's possible e.g output + 1n

``````6145390195186705543n + 1n

6145390195186705544n

``````

You can check how I used this to solve a problem on leetcode:

My Solution

``````var plusOne = function(digits) {
let fin=[]
let comb =singleValue(digits)
comb = BigInt(comb)
comb = comb +1n
let arr = comb.toString().split('')
for(let i=0; i<arr.length; i++){
fin.push(Number(arr[i]))
}
return fin

};

function singleValue(arr){
let str = ""
for(let i=0; i<arr.length; i++){
str +=arr[i]
}
return str

}
``````