Using this math trick, you will be able to square any two digit number very quickly. With a little practice you can do it in your head, or you can do it on paper and still impress others with your math skills. This method of squaring is very easy, and I will be using as an example squaring the number 23.
First, determine the closest number to your number that ends in a zero. In this example, the number is 20. Next, determine the difference between your number and the closest number with the zero. In this case, it will be (23 – 20) = 3. Add the result to your number (23 + 3 = 26). Now, multiply the number with the zero by the sum of your number and the difference you determined:
20 x 26 = 520
Now square the difference you determined before, and add it to the result above:
(3 x 3) + 520 = 529
Presto! There is the square of your number!
Here are some more examples:
The Square of 25
Closest zero number: 20 (note – 30 will also work in this example)
Difference: 25 – 20 = 5
Sum: 25 + 5 = 30
Answer: (5 x 5) + (20 x 30) = 25 + 600 = 625
The Square of 37
Closest zero number: 40
Difference: 37 – 40 = -3
Sum: 37 + -3 = 34
Answer: (-3 x -3) + (40 x 34) = 9 + 1360 = 1369
The Square of 81
Closest zero number: 80
Difference: 81 – 80 = 1
Sum: 81 + 1 = 82
Answer: (1 x 1) + (80 x 82) = 1 + 6400 + 160 = 6561
Noticed how I broke down the (80 x 82) into (80 x 80) + (2 x 80)!
The Square of 12
Closest zero number: 10
Difference: 12 – 10 = 2
Sum: 12 + 2 = 14
Answer: (2 x 2) + (14 x 10) = 4 + 140 = 144
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