We are going to look at different unit conversions in this section.

To go down the list, we multiply by 1000. For example, if we were converting micrometres to nanometres, we would multiply by 1000.

To go up the list, we divide by 1000. For example, if we were converting micrometres to millimetres, we would divide by 1000.

Let’s have a few examples.

To go up the list, we divide by 1000. For example, if we were converting micrometres to millimetres, we would divide by 1000.

Let’s have a few examples.

**Example 1**

Convert 6 nanometres to picometres.

We convert nanometres to picometres by multiply by 1000. Therefore, we multiply 6 by 1000.

This tells us that 6 nanometres is 6,000 picometres (6,000 pm).

**Example 2**

Convert 7.2 nanometres to micrometres.

We convert nanometres to micrometres by dividing by 1000. Therefore, we divide 7.2 by 1000.

This tells us that 7.2 nanometres is 0.0072 micrometres (0.0072 μm).

**Example 3**

Convert 8.5 mm to nm.

This question is asking us to convert millimetres (mm) to nanometres (nm). With this conversion, we are essentially going through two conversions; millimetres to micrometres, and then micrometres to nanometres.

We convert millimetres to micrometres by multiplying by 1000, and then we convert micrometres to nanometres by multiplying by 1000. Therefore, we convert millimetres to nanometres by multiplying by 1000 twice.

This tells us that 8.5 mm is 8,500,000 nm.

**End Note**

The prefixes milli, micro, nano and pico will always follow these rules. Sometimes in chemistry we will be working with very small masses, and we will need to convert grams to milligrams (or vice versa); we convert grams to milligrams by multiplying by 1000.

Also, it is worth getting the unit table at the top down on a revision card as the units come up a lot and are fairly easy to forget.