Calcluting odds

[elwoodblues]

I'm relatively young in terms of poker experience and had a question about calculating odds. Because so many calculations at the table are done in your head, is there an easier way to do the mental machinations than using your fingers and toes?

For Hold 'em, I have resorted to always using the number 48 for unseen cards (regardless of whether it is on the flop, turn, or river). 48 tends to be easier to work with than 47 in that it is divisible by so many numbers. Will using 48 affect my calculations in any significant way? Does anyone else have any good tips?

Thanks in advance!

Elwood