function modify(num) {
    let numAsStr=num.toString();
    let sum=sumDigits(numAsStr);
    while (sum/numAsStr.length<=5){
        numAsStr+='9';
        sum=sumDigits(numAsStr)
    }
    console.log(numAsStr);
    function sumDigits(numAsStr) {
        let sum=0;
        for (let digit of numAsStr) {
          sum+=Number(digit);
        }
        return sum;
    }
}