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Sum of digits
A checksum routine needs the digits of a number added together.
- Negative input uses its digits too: -204 sums to 6.
- The digits of 0 sum to 0.
digitSum(amount: int) → int
Where you start
function digitSum(amount: number): number {
}Worked examples
| Call | Result |
|---|---|
digitSum(0) | 0 |
digitSum(7) | 7 |
digitSum(1234) | 10 |
digitSum(-204) | 6 |
Hint
Take the absolute value first, then peel digits off with % 10 and / 10.
Reference solution in TypeScript
function digitSum(amount: number): number {
let x = Math.abs(amount);
let total = 0;
while (x > 0) {
total += x % 10;
x = Math.floor(x / 10);
}
return total;
}