If multisim is a circuit simulator. It will take care of this for you. So just use component value. In Pspice you can use these component suffix. I think they are legal in multisim also. They may also case insensetive (I think not sure )
PSPICE Power-of-Ten Suffix Representation:
F fento- 10-15
P pico- 10-12
N nano- 10-9
U micro- 10-6
M milli- 10-3
K kilo- 10+3
MEG mega- 10+6
G giga- 10+9
T tera- 10+12
MIL (0.001") 25.4×10-6
No I do not think so. But why do you want to this? Do want to simulate closed loop system? For that kind of simulation it is better to use Control Design and Simulation software tools