My Math library to help my daughter with her homework.

Maths.js

export const roundWholeNumber = (_num, _places) => {
    const num = String(_num)
    const places = String(_places)

    if (isNaN(parseInt(num)) || isNaN(parseInt(places))) {
        return
    }

    if (places.length > num.length) {
        return
    }

    const padSize = places.length - 1
    const roundDeciderIndex = num.length - padSize
    const roundDecider = num[roundDeciderIndex]
    const sliceSize = num.length - padSize > 0 ? num.length - padSize : 1
    const roundee = parseInt(num.substr(0, sliceSize))
    const rounded = parseInt(roundDecider) > 5 ? roundee + 1 : roundee
    const padding = Array(padSize).fill('0').join('')

    return `${rounded}${padding}`
}

export const truncateToPlace = (_num) => {
    const num = parseInt(_num)

    if (isNaN(num)) {
        return
    }

    return `1${Array(String(num).length).fill('0').join('')}`
}