Divisibility Test of 3: How It Works?

We need to see if a large number is divisible by 3. What do we do? Long division is one way. But we can simplify our work just by adding the digits of the given number. We know that if the sum is a multiple of 3, so is the given number. This is popularly referred as the ‘Divisibility test of 3’. But how does this work? What is the mathematics behind this trick? We explore it in this video.

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