Percent composition help [chemistry]

Ok well I kind of get how to do this as I have an example here and I have to do others...

This one for example is done...but i need help

Determine percentage composition

First you find the formula mass...

Calcium nitrate Ca(NO3)2

Ca 1x40=40
N 2x14=28
O 6x16=96

added all together you get 164 then you do 164 divided by the 40,28,and 96 x 100% to get the percentage..

I was wondering if you look above were I did the Ca,N,O with 1,2,6

How do you figure out those numbers like the 1,2,6?? im having problems with that or those it stay same for all problems..? how do you figure out the number before you multiplty it with the mass

 

Read the stickies.

Moved to help and requests.

 

Look at it mathematically.

There is 1x Calcium
There is 2x (NO3).

What you need to do is distribute the 2 giving you two Nitrogens and a total of 2 O3 molecules, which is a total of 6 Oxygens.

This gives you the

1 Calcium
2 Nitrogens
6 Oxygens