He would have done 10+10+10 like for each stick then + How ever many ones there were and then we would have done the same for the other set . Soorry if I'm wrong
In the real world you are not going to have a calculator on you 24/7. Nor will you have a pencil or paper to do longhand. You need to know how to accurately estimate your answers in order to be successful.
By definition, the number
is the ratio between the circumference and the diameter:

This implies that

And so your circumference is 
Let the maximum number of pages Jennifer can have be = x
Amount Jennifer has (P) = $62.10
Given equation is :
P = 
Price is given = 62.10 , so equation is :




Hence, Jennifer can have a maximum of 68 pages in her book.