# How to convert kilograms to milligrams and tons to ounces | Khan Academy

Here I have two tasks for converting units of measure. I want to convert 3 pounds to milligrams. And I want to turn 4 tons into ounces. This is in the metric system. And that is in the American Measurement System. I advise you to stop the video and try to convert the units yourself. To do this, we must let us first consider what these prefixes mean. I can save this as 3 pounds and we will turn them into any amount of milligrams. We already know that the prefix ‘kilo’ literally means 1000. And the prefix ‘miles’ means 1 per 1000 or 1000 of one gram. Let’s turn grams first. Kilograms in grams. And then from the grams we will find the milligrams. So we can say that 3 kilograms will be equal to 3 per 1000 grams. This equals 3000. That’s 3,000 grams. This is one way to interpret ‘kilo’. And it brings us to 3000 grams. But how do we get from grams to milligrams? We already said that 1 milligram – let me record it here – 1 milligram equals 1 per 1000 or 1 thousand of one gram. Another way to think about this statement is that 1 gram equals 1000 milligrams. If we think about it, we have 3000 grams, each equal to 1,000 milligrams.

So that’s equal to 3000 grams. Each is equal to 1000 milligrams. 1000 each. And that will give us the number in milligrams. How much will that be? 1000 thousand is one million, so 3000 is 3 million That will give us 3 million milligrams There is another way to think about this multiplication – I have 3 zeros here, so my work needs… 3 by 1 is 3 and then they have to follow these 6 zeros, so I get 3 million milligrams. Let’s do the same here Let’s turn the standard unit of measure into a unit of measure in the American system – ounces. Here’s what we will do – first we will turn into pounds, and then from pounds to ounces. We know that there are 2000 pounds in one ton So 4 tons will be equal …

For each of them we have 2000 pounds. So it’s going to be 4 to 2,000 pounds, which is 8000 pounds. I’ll leave some space here. And now, how many ounces is there in every pound? Well, we know that 1 pound contains 16 ounces. Let me record here – 8000 lbs. If there are 16 ounces in each of those 8,000 pounds, this will give us 8000 by 16 ounces. What is 8000 by 16? That will be 8 times 16, which is 80 plus 48, becomes 128.

But we want 8000 times, so it will be 128 000. 4 tons is … many ounces. 