how do you put in a faction on a scientific calculator?

Depends which calculator.

For the web2 calc on the home page look here.

http://web2.0calc.com/questions/how-do-i-type-in-fractions

For others try googling it.  Most times you get answers that way for these types of questions.  

a+b-c+d*8=(a+b-c)+(d*8) i hope that will be helpfull!