nf() not rounding correctly fixed

[aditya-shrivastavv]

Resolves #5959

File Changed = src/utilities/string_functions.js

Problem:

• nf() call doNf() when it detects a number
• previously the doNf() was just truncating the number i.e. not rounding off

Changes:

• inside doNf() , i added another utility function which rounds off the decimal part of the number correctly
• the added function named roundOffDecPart modifies the decPart but does not truncate it.
• the modified decPart is return to the doNf() which then truncates the decPart according to the right value.

Outcomes of the change:
As mentioned in the issue decription, the improper rounding of the digits of Math.PI is fixed successfully.
Successfully tested it many times at all sorts of possible inputs

PR Checklist

• npm run lint passes
• Inline documentation is included / updated
• Unit tests are included / updated

[welcome]

🎉 Thanks for opening this pull request! Please check out our contributing guidelines if you haven't already. And be sure to add yourself to the list of contributors on the readme page!

[limzykenneth]

Hi @aditya-shrivastavv, in #5959 @akp660 has already indicated and been assigned to work on the issue so I will be prioritizing their work on this and I'm going to close this for now.

PS. Also as mentioned in #5710, Number.toFixed() is a possible solution and there's no need to manually implement rounding.

[aditya-shrivastavv]

okay then let this be closed for now. I will try to implement it with Number.toFixed(). If the assignee is not able to work through it. this PR will be helpful