Digit Sum | Digit Product
Calculate Digit Sum
The digit sum is the sum of the ciphers of a number. To calculate, just type or paste any text with numbers into the field and press Calculate digit sums. Characters, which aren't numbers, are counted, but ignored for the digit sums. For the alternating digit sum, the numbers are alternatingly added and subtracted: z1-z2+z3-z4+z5-... . For the iterated digit sum, the digit sum is executed until the result is one-digit.
Example: the digit sum of 1234 = 1+2+3+4 = 10
If a number is divisible without remainder by 3 or 9, then the same is true for its digit sum and vice versa. Furthermore, digit sums are used as checksums for number values.