Very Simple method, just put zero's instead of last digit, its become the values in pico farad. for example 224, it means put four zero's with 22, i.e 220000 pF, if 103 is written put three zero's with first two digit. i.e. 10000 pF.
Divide the pF value by 1000 it becomes nF and then again divide (nF) by 1000 it become uF.