Thanks for the reply. The reason I didn't use scanf and printf is I'm using a 4*3 matrix keyboard (which is in parallel) and an LCD (parallel too). I would want a portable device, so I need to keep things as small and as simple as possible, hence the matrix keyboard or keypad. To my knowledge, scanf and printf are for reading and displaying in serial only.

Yup, the 8051 only sees binary. However, when I use a compiler, I normally input in hex or decimal, hence, the 8051 'understands' this. If I press the key on a keypad, all I get are plain signals, thus the compiler could not 'see'it at all.

Pranav, I've found the math library. It seems to be a bit large though. I hoped to minimize code size as much as possible