Squaring of Integers in 2 easy steps!

I just figured out this amazing way of squaring numbers with ones digit 5. Suppose you need to find out the square of 35. Then simply square 5 and write down 25 at last and then multiply 3*3 and add 3.That is square the remaining numbers except 5 and add the same value.You will get 12.Since you can also write it as 3 (3) + 3 = 3 (1 + 3) = 3 *4. So,you may just as well multiply the next integer. You can now easily write 35^2 = 1225. In case of another no.,say 125,you take 25 at last and multiply 12 * 13.So,you have 15625. If you are more comfortable in squaring,simply square 12,you'll get 144 and then add 12,you will get 156.So,125^2 = 15625. Rule works for no. whose ones digit is 5. You will probably not find this anywhere else.It was something I came up with while randomly squaring integers.

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`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
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Very good that you $\color{#D61F06}{rediscovered}$ this yourself. You may be interested in knowing that square of any two and three digit numbers can be found as under. $(10a\pm b)^2$ write square of a and then of b. (if b is 1, 2 , or 3, write its square as 01, 04 or09) to this $\pm$ 20 times a*b. Say $37^2 = (30+7)^2=\color{#D61F06}{9} \color{#3D99F6}{49} +20*21 = 1369. \\37^2 = (40-3)^2=\color{#D61F06}{16} \color{#3D99F6}{09} -20*12=1369 ~\\ Three ~digit~ number ~the ~same ~way~~\\127^2 =(120+7)^2= \color{#D61F06}{144} \color{#3D99F6}{49} +20*84=16129 \\127^2 = (130-3)^2=\color{#D61F06}{169} \color{#3D99F6}{09} -20*39=16129\\With~5~at~ unit ~place ~it ~is ~ easy.~~~ (10a +5)^2= \color{#D61F06}{a*(a+1)} \color{#3D99F6}{25}.\\125^2=(120 +5)^2= \color{#D61F06}{(12*13)} \color{#3D99F6}{25}= \color{#D61F06}{156} \color{#3D99F6}{25} .$

Niranjan Khanderia - 6 years, 5 months ago

Amazing! Thank you.

Titas Biswas - 6 years, 5 months ago

I have made an addition.

Niranjan Khanderia - 6 years, 5 months ago

@Niranjan Khanderia – Thanks again.Learnt 2 more ways at a go.

Titas Biswas - 6 years, 5 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$