# Video: Understanding Unit Prefixes

How many grams are there in 1 kilogram?

02:10

### Video Transcript

How many grams are there in one kilogram?

In order to answer this, let’s underline the key words in the question. So grams, obviously, is a keyword. We want to find out how many of those there are in one kilogram. So let’s first discuss what a gram actually is, in the first place.

A gram is a metric unit of measurement. And it measures mass or the amount of stuff in an object. So we know what a gram is. But what is a kilogram? Well, kilo is a prefix which means that you can use it before other words to make a new word. And the kilo prefix means 1000. In other words, a kilogram means 1000 grams. So the answer to our question is: there are 1000 grams in one kilogram.

Now before we go, we did mention earlier that kilo is a prefix. That means that it can be used in front of other words, not just gram. Examples include kilometer, where a meter is a measurement of distance. And a kilometer means 1000 meters. Kilohertz, where hertz is a frequency measurement. And guess what, kilohertz is 1000 hertz, and so on. A good idea is to try and write down as many words as possible with the prefix kilo in them and work out what they mean. They most probably mean 1000 of something.

Another interesting point is to contrast the prefix kilo with another prefix milli. Milli in some sense is the opposite of kilo, in that if there are 1000 grams in a kilogram, a milligram is a 1000th of a gram. So with kilo you’re multiplying a gram by 1000. With milli, you’re dividing a gram by 1000. And of course, it doesn’t have to apply to a gram necessarily. You can apply it to other words as well, such as a millimeter which is 1000th of a meter. And maybe even a millipede which is supposed to have a thousand legs so each leg gets a thousandth of the body. Sure, that works.