To convert from kilograms to milligrams, first multiply by what to convert to grams, and then multiply by what to convert to milligrams.
Let’s just take a moment to think about these words, kilogram, gram, and milligram. They’ve all got the word gram in common. Now a gram is a units of weight in the metric system, and kilo and milli are prefixes that mean different things.
Kilo means a thousand. So a kilogram is a thousand grams. And milli means a thousandth. So a fraction of a thousandth of a gram is a milligram.
So if you think about it, there are a thousand grams in a kilogram. Then there must be a thousand milligrams in a gram. So is a gram a “millikilogram”, a thousandth of a thousand grams? Well the word “millikilogram” doesn’t actually exist. But if it did, yes that’s what it would be.
Okay. Let’s think about one particular example then. As we’ve said, one kilogram is a thousand grams. So to get from the number of kilograms to the number of grams, we had to multiply that number by a thousand. And since a milligram is a thousandth of a gram, every gram has a thousand milligrams in it. So each one of these thousand grams has another thousand milligrams in it. So we’re gonna need to multiply that number by a thousand in order to convert it into milligrams. So a kilogram is a thousand grams, which is a million milligrams.
So going back to our question then, we can fill in the gaps. To convert from kilograms to milligrams, first multiply by a thousand to convert to grams, and then multiply that answer by a thousand again to convert to milligrams.