I beg my readers’ pardon, but I’m 500 miles from my kids and want to do what I can to help them with their homework. I created this page to help them with metric conversions.

The metric system is based on powers of 10. To convert from one metric unit to another of the same kind, all you need to do is move the decimal point. In the helper chart, each box represents a place value: the unit box (meter, liter, gram) is the ones, Deka is the tens, Hecto is the hundreds, and kilo is the thousands. To the right of the units column, deci is tenths, centi is hundredths, and milli is thousandths.

Let’s say you want to convert 4 meters to centimeters. Here’s how you do it.

Place the four in the meters box like this:

Now place the decimal in the lower right-hand corner of the measure to which you want to convert. In this case, we’ll place it in the centi(meter) box, like this:

Now fill in any empty boxes between the number and the decimal (including the box with the decimal) with zeros (0’s), like this:

And there you have your answer: 4 meters = 400 centimeters

Now let’s try something different.

Let’s say you want to convert 7000 meters to kilometers. Here’s how you do it.

Because each box is a power of 10, we’re going to put one number in each box, with the last digit on the right in the box that has our original unit. In this case, our last digit is zero, and our unit is meters, so we’ll put a 0 in the meters box and fill in the rest of the boxes to the left with our number:

Now place the decimal in the lower right-hand corner of the measure to which you want to convert. In this case, we’ll place it in the kilometer box, like this:

Unless you need significant figures (if you don’t know what those are, don’t worry about it yet), start from the right and cross out or erase all zeroes until you get to a digit that isn’t a zero. In this case, all of the digits to the right of the decimal are zero, so we can remove them all.

And there you have your answer: 7000 meters = 7 kilometers.

Now let’s try one more:

Let’s say you want to convert 35 millimeters to meters. Here’s how you do it.

Because each box is a power of 10, we’re going to put one number in each box, with the last digit on the right in the box that has our original unit. In this case, our last digit is 5, and our unit is meters, so we’ll put a 0 in the meters box and fill in the rest of the boxes to the left with our number:

Now place the decimal in the lower right-hand corner of the unit to which you want to convert. In this case, we’ll place it in the meter box, like this:

In this case, we have an open box to the left of the number between the number and the decimal. Just like the first example, fill in the empty boxes between the number and the decimal, including the box with the decimal, with zeroes.

And there you have your answer: 35 millimeters = 0.035 meters.

Here are some blank boxes that you can practice on.