This super-easy maths trick is sure to shock you

Updated Feb. 5, 2026, 8:15 a.m. | By Jacaranda FM

We bet you didn't know about this wild maths trick.

Depending on who you ask, maths can either be thee worst nightmare or the best thing in the world.

That being said, there’s no denying that maths can sometimes be really cool.

Breakfast with Martin Bester recently came across a clever maths trick that we bet you’ve never heard of before.

For every number above nine, if you subtract the value of each individual digit from the number itself, the result will always be divisible by nine.

For example:

12 − 1 − 2 = 9 (and 9 is divisible by 9)

23 − 2 − 3 = 18 (and 18 is divisible by 9)

197 − 1 − 9 − 7 = 180 (and 180 is divisible by 9)

The same also works for the number three

The exact same method applies when checking divisibility by three.

12 − 1 − 2 = 9 (divisible by 3)

23 − 2 − 3 = 18 (divisible by 3)

197 − 1 − 9 − 7 = 180 (divisible by 3)

There's also another useful rule involving the number nine.

A number is divisible by 9 if the sum of its digits is also divisible by 9.

For example:

Check if 567 is divisible by 9.

Sum the digits: 5 + 6 + 7 = 18

Check divisibility: 18 ÷ 9 = 2 (a whole number)

Since the result is a whole number, 567 is divisible by 9.

More examples of divisibility by 9

729: Sum of the digits = 7 + 2 + 9 = 18, which is divisible by 9. So, 729 is divisible by 9.

5463: Sum of the digits = 5 + 4 + 6 + 3 = 18, which is divisible by 9. So, 5463 is divisible by 9.

Tune in to the 'Breakfast with Martin Bester', weekdays from 06:00 - 09:00. Stream the show live here or download our mobile app here.

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Images: Instagram/ Springboks