Even if you don't regularly use the metric system terra, giga, mega, kilo, milli, micro, nano and more prefixes are useful to know and be able to convert between, they are being used in more and more measurements systems.
This technique is so fast and easy it'll have you speeding through your equations.
Some measurement systems that use these are;
Watts, volts, ohms, amps, bytes, joules, meters, litres, grams, seconds, hertz, pascals, newtons, and many more.
Step 1: Draw Your Base Chart
Draw the picture.
Draw lots of 000,s with decimal points between them and either the prefix or its symbol (whichever you prefer) allighned with the appropriate decimal point.
Draw whichever ones you will be using, there's no need for pica's if your working in bytes.
Step 2: Draw in Your Number
Draw your number in its place over (or above) the 000's.
Use its current prefix and put the decimal point at the point labeled with that prefix.
If there is no decimal point in your number the point is straight after your number.
Step 3: Choose Your New Prefix
Choose the prefix you wish to use, or wish to turn this into.
Put the new decimal point where the decimal point with your desired prefix is.
Fill in any blanks spots between the written number and the decimal point with 00000's
You have your number.
If you have any questions feel free to ask.