# 2: Metric conversions: step to the right, step to the left

First, the basics. One metre (which is oddly enough just about the same size as a metre stick) can be divided into 1000 parts called millimetres. So, if I want to convert a measurement in millimetres to metres, I can do it by moving the decimal point 3 places to the left:

277 mm -> 0.277 m

Likewise, if I want to convert a measurement in metres to millimetres, I can do it by moving the decimal point 3 places to the right:

0.341 m -> 341 mm

If you don’t have any decimal places to move to the right, then you need to add zeros:

345 m ->345000 mm

34.5 m ->34500 mm

A lot of people remember the part about moving the decimal point over by 3, but dont remember whether it goes to the left or the right. Theres an easy solution for this: make sure your answer makes sense! Millimetres are pretty small. Its going to take MORE millimetres than metres to make the same measurement.

A few big units = Lots of small units If you convert the length of your finger (70 millimetres) into 70,000 metres, stop and think a moment. 70,000 metres is pretty ridiculous.

If you divide a millimetre into 1000 pieces, you get a micrometre, abbreviated µm, or um (being easier to type on a standard keyboard).

And if you divide a um into 1000 pieces, you get a nanometre, or nm.

So altogether now:

• 1 metre is 1000 millimetres
• 1 millimetre is 1000 micrometres (or microns, or µm, or um)
• 1 micrometre is 1000 nanometres (or nm)