Definition
Digit sum
A digit sum is the total you get by adding every digit in a numeral.
What it means
Read the numeral one digit at a time and add those digit values. Place value does not change what each digit contributes: in 5,084, the 5 contributes 5 to the digit sum, not 5,000.
Remember it
Ignore the commas and place-value sizes; collect the digits and add them.
Example
For 5,084, add 5 + 0 + 8 + 4 = 17. Its digit sum is 17.
Watch for
A digit sum is not the value of the numeral: 5,084 and 17 are different numbers.
Common mix-up
Add each digit’s own value; do not multiply it by its place value.
Exact meaning
The digit sum of a numeral is the sum of the numerical values of all its digits.