Given a long number, return all the possible sum of two digits of it. For example, 12345: all possible sum of two digits from that number are:
function digits(num){
let numArray = num.toString().split('');
let sumArray = [];
for (let i = 0; i < numArray.length; i++) {
for (let j = i+1; j < numArray.length; j++) {
let sum;
sum = Number(numArray[i]) + Number(numArray[j]);
sumArray.push(sum);
}
}
return sumArray;
}