Lemma
EasyDivisibility
#24 · Number Theory · Divisibility

The nine test

What is the remainder when 123,456,789 is divided by 9? (You can find it without dividing.)

~4 minWritten answer · compare with the solutionDigit sumsDivisibility by 9
Stuck? A gentle nudge
Something off?
Workspace
Your working

Check your full solution

Upload photos of your handwritten work or a PDF, and Lemma will read it and tell you whether it's right — and where it first goes wrong if not.