Digit Sum

How to play Digit Sum

1. Add all the digits of a number without losing your place.
2. Read the prompt carefully and choose an answer, or type into the answer field.
3. After checking, read the explanation. Use “Next round” to continue.
4. Complete ten rounds for a score out of 100. Restart creates a fresh session.

A worked example

Add the individual digits. 5199

the answer is 24. Add each digit once.

A useful way to practice

Work out a rough answer before checking the options. If a result surprises you, use the explanation to identify the step you missed. Accuracy is more useful than rushing through a rule you have not understood.

What your result means

This is a recreational numbers activity. Results describe performance on this particular task, with this device and these rules. They are not a clinical assessment, IQ score or promise of improvements in daily life. Your best result and recent sessions stay in this browser; no account is required.