Square Roots.

[ChristmasTrulyReigns]

Been a long time since I was at school, but I've been helping DD2 with her homework, and I'm pretty sure that you can't work these out mentally?

Or is there a technique that I can show her?

TIA.

Only method I know is to pick a number you think it might be and then square it and see if it's too high or too low.
Pick another number and square it, hopefully it will be on the other side
Then take the difference between the 2 and square it. If it's too low, then it replaces the previous 'too low' number. Etc.
Then half the difference...

Does that make sense. So, if you were trying to find the sq rt of 17 you might pick 4 - squared is 16 so too low. Try 5 - 25, so way too high. So pick 4.5 - square it, 16.25, too low, so replaces 4 as your 'too low' number. So half again between 4.5 and 5 - 4.75, square it and so on. Stop when you've reached the right number of decimal points.

How old is she, Christmas?
If she is primary,
I would just teach her all the square numbers to 12 and that the root is the opposite as in times / divide.

oh yeah there's that method too

Thnks Stealth, that's how I was expalining it to her, but not quite so eloquently.

Just wondered if there was a scientific (or whatever the word should be) approach.

I'm glad someone has come on who can guide me, I posted this in the wrong topic originally, and my word, those Foodies were useless.

There must be a method involving baking a cake of a specific volume and then measuring the length of it's side ...

It's called the Newton Raphson method I think

Foodies are fine for ratio and proportion, but not much use for anything else

I think they're just not trying tbh. No sense of commitment.

Yup that's the way to do it. If she's getting into it read The Number Devil with her - fab book all about square numbers, triangle numbers, prime numbers, Fibonacci series etc...or just read it to yourself.

Just ordered it thanks Hima - we have got a Murderous Maths book, but more always welcome.

We had a 'square root' table in our 'Log Tables' at school. There is a way if the answer is a whole number. You can use factor trees.

There is a method but that was A'level in my day so could be degree level now. Try explaining it in terms of areas of squares. So if a square has an area of 4 what length are its sides?

what you do is make a tree breaking down the number to be a product of only prime numbers .Yo start with the number ,say 36, and choose two numbers which you can multiply together to make it (say 2 and 18) 2 is a prime number, so that branch is finished.Look at 18 choose 2 numbers that you can multiply to make it say 6 and 3 is prime and 6 is 2x3, both primes.Therefore you have the prime numbers 2,2,3,3.Put these into 2 identical sets.In this case each set will have a 2 and a 3 in it.Multiply them together and voila you get 6