Thread: changing accuracy of output from an input value

im trying to set the accuracy of an output by a value which is input.

ive got the number coded in etc, and im trying to determine how many numbers should appear after the decimal place.
atm i have

Code:

%8.zlf

where z is the input number, but all it does is displace zlf, any tips/clues/rants directed at me would be appreciated

i just found out its using the switch function, so please ignore my ignorance