Enter Number

Calculate the digit sum of 99

Calculate the reduced digit sum of 99

Add up 2 digits of 99:

Digit Sum → 9 + 9 = 18

Since our digit sum > 9:
repeat this process to get the reduced digit sum:
Our new number to evaluate is 18

Add up 2 digits of 18:

Digit Sum → 1 + 8 = 9

Since our digit sum ≤ 9:
we have our reduced digit sum

Final Answer


Digit Sum = 18
Reduced Digit Sum = 9