How to Calculate Square Roots without a Calculator | Mental Minute Math

In this video we learn How to Calculate Square Roots without a Calculator. This is a mental math trick that you can use to approximate the square root of a number without using a calculator. This is a nice mental math trick!

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[TheRoViator]

can we take a minute to appriciate this guys backwards writing ability

[hollyrylatt-price]

Okay but not all of us can easily convert fractions to decimals, so now I gotta revise that real quick

[PuckCurtis]

We just found this video tonight and my family wanted to express our thanks for this method. As soon as my guy watched you do it, he rushed back to his homework and started cranking. Having two examples also makes it easier to follow your logic. Very well done.

[olerocker]

Since calculating in my head is easier for me I find how many steps it is from 16 to 25 (9), subtract 16 from 19 and the fraction value is 3/9 or .333. Add that to 4 and you get an approximation of 4.333.

[kazimierzkoszel]

Hey I'm curious about how did you made that, that you write on whiteboard and at the same time we can see it from opposite perspective? did you learned to write in reverse or something?

[HemasChalkboard]

Thanks a ton. That was simple and a great help for my upcoming NEET exam.

[rubikscube]

Thank you so much i need this for tomorrows test now i can do it 🎉thanks

[jeffw]

This method is even more effective if you memorize all the squares up to 100. So instead of the square root of 19, I'd add two zeroes and take the square root of 1900. 43^2 is 1849, and 44^2 is 1936, so the first two digits are 43 (I can place the decimal point at the end). 1900 is 51/97 of the way between 43 and 44, and by inspection I can see that the next digit is a 5. So I already know the answer starts with 4.35.
A linear approximation begins to deviate from the true value after we double the number of significant digits, so I use this method to go from three digits to six digits, then from six digits to twelve digits, etc.
And... I do it all in my head.

[san]

This method does not work when the value is far away from previous square. Try this method for 13 or 99, for example. What is the point in multiplying by 1/2...

[lexilou]

thanks i needed this for my final exam tmrw

[PrithwirajSen-njqq]

√36=?
5^2=25
36-25=11
√36=5 + 11/5*2=5+1.1=6.1
Here approximation results to higher than actual as we know √36=6
Hence please clear the theme u used

[jonney]

What if it’s sqr3 there’s nothing i can get before the 3

[adnanhussain]

so..what will be the answer of root24 with this method?

[cheynegwenethfernando]

Am I the only one curious on how he writes it on an opposite perspective?

[Hi-szyg]

I know hard question to ask but how does that rule intuitively work.

[doombuggy]

It always drove me crazy that none of my math teachers ever gave me a method to find a square root without a calculator. This method is super helpful, but it still requires you to memorize perfect squares though. I really just want a formula for finding the square root of any number.

[annyag]

Can anyone explain why divide 2 or times 1/2?

[johnmichael-jjwd]

Give me an extra minute… I’m falling asleep

[tessfowler]

We tried it on sq rt of 15, and it didn't work.

[jamessmith]

I got here because I'm trying to find out if it's possible getting the square root of a number without a calculator and I can't really use this because I'm dumb or it's just too advance for me lol

First I don't know how to divide something like 3÷8 maybe 8÷3 like 2.33? (That took me several seconds and it's wrong I check the calculator)

The best I can do that took couples of second will be 3+3 and 15+17 and 135+57 which took several seconds and I tried to do a hard one like 135×57 my answer is 7, 435 and it's wrong and it took almost 4 minutes lol

And the video said find the perfect square root of the number so how am I going to find the nearest square root of 7, 695? Lol I guess this only works on 2 to 3 digit numbers or someone that was just very good at math

My mental math will be average at best and I guess this will not be a problem unless in the future that we need to somehow solve a calculus problem without calculators or formulas lmao (I hope I just did not jinx myself because I'm definitely screwed if that happens)