Sum of Digits Calculator
MathAdd up all the digits in a number.
Sum of Digits
The total obtained by adding every digit in the number together.
Divisibility Check
Whether the digit sum reveals the number is divisible by 3 or 9. Digit sum is divisible by 3, so the number itself is divisible by 3, but not by 9.
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Creators
Odeh Ahwal0people find this calculator helpful
Views
Helpful
Saved
Embeds
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Frequently Asked Questions
How do I find the sum of digits?
Break the number apart into its individual digits and add them all together. For example, the digits of 12345 are 1, 2, 3, 4, and 5, which add up to 15.
Why does digit sum matter for divisibility?
A number is divisible by 3 exactly when its digit sum is divisible by 3, and divisible by 9 exactly when its digit sum is divisible by 9. This is a quick shortcut for checking divisibility without doing the actual division.
What happens with negative numbers?
The calculator uses the number's absolute value, since digit sum is a property of the digits themselves, not affected by a leading minus sign.
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