luhnValidityCheck()

function luhnValidityCheck(value: string | number): boolean {
  const numbers = value.toString().split('').reverse()
  const sum = numbers.reduce((sum, number, index) => {
     let n = Number(number)
     if (index % 2 !== 0) {
       n *= 2
       n -= n > 9 ? 9 : 0
     }
     return sum + n
  }, 0)
    return sum % 10 === 0
}