Add/Subtract

Multiply/Divide

Powers/Roots

Integrate/Differentiate

If you can do something in maths, then someone is bound to say "can you go backwards?"

]]>if xy = 1, then x and y are reciprocals of eachother, so if you know x = 2 you know y = 1/2. Of course solving for x or y does the same thing but its slightly faster to just take the reciprocal.

Likewise, if xy = 5, then x = 5 times the reciprocal of y and y = 5 times the reciprocal of x. Of course you can just solve for x or y but I find it faster to simply take the reciprocal and multiply times 5.

So obviousy if xy= n then x = n/y and y = n/x but if I think of it as x = 1/y * n, or y = 1/x*n its slighty faster to do in my head, for me at least.

Likewise, if xyz = 1, then the product of 2 of the variavles equals the reciprocal of the other, and I think if xyz = n, then the product of 2 of the variables will equal n times the reciprocal of the other.

I find its just good to be aware of this, it tends to speed things up.

]]>