I need to convert 7 digit long int xxxxxxx become string "xxx.xxxx" and send the string over serial.print. Converting the long to float : float reg=xxxxxxx/10000.0 than send it with serial.println(reg,4) Obviously it works, but i guess this is not the most effective (both in speed or size) since it introduce (unnecessary?) floating point operation. any thoughts ?

sterretje:
Divide by 10000 to get the number before the decimal dot; use the modulo 10000 (the mod operator '%') to get the part after the decimal dot.

problem with modulo operator is how to pad with '0' if remaining/fraction part is started with digit 0.
example if the fraction is .0125, it will give .1250.
But i will try it..