Metric Conversion

Imagine a motor racer zooming down the track. It travels one hundred twenty three centimeters. But scientists and engineers don't usually measure with centimeters. They use meters.

Since we're exploring rate, graphing, and algebra, we'll do the same. So here's the big question. How many meters did the motor racer travel?

One hundred centimeters equals one meter. That's our conversion fact. So, to go from centimeters to meters, we need to divide by one hundred.

Now, here's where people get mixed up. Some just say, just move the decimal point two places. But actually, the decimal never moves. It's the digits that slide into new place value spots.

Let's look at a place value chart. As we move left along the place value chart, each column gets ten times bigger than the previous one. As we move to the right along the place value chart, each column is ten times smaller than the previous one. It's like dividing by ten.

Let's start with the number one hundred twenty three, placing each digit in the proper place value column. Dividing by ten means every digit slides one column to the right.

When we divide by one hundred, that is simply dividing by ten two times. Each digit will wind up sliding two columns to the right.

So one hundred twenty three centimeters becomes one point two three meters. Notice how the decimal and each column on the place value chart stayed in the same spot. It's the digits that moved.

Now let's solve it on paper using a similar digit slide method. We start with one hundred twenty three. Even though there's no decimal place written, it would come after the three ones. You can think of it as one hundred twenty three point zero zero.

When we divide by ten, the digits all slide one place to the right. Twelve point three. That decimal point is fixed and will always stay in the same spot.

Divide by ten again, they each slide one more place. One point two three.

So dividing by one hundred is the same as dividing by ten twice. That's how one hundred twenty three centimeters becomes one point two three meters.