Have you ever raced a friend across a pool or lake? What if you had been timed? What if the difference between winning and losing came down to a tenth of a second or a hundredth of a second? Comparing decimals is often necessary in competitive swimming.

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For Olympic swimmer Michael Phelps, the difference between winning gold and silver in one event at the 2008 Summer Olympics came down to comparing decimals. He finished the 100-meter Men’s Butterfly with a time of 50.58 seconds—Milorad ?avi? finished with a time of 50.59 seconds!

Now you may be wondering what this has to do with comparing decimals. First, take a look at the times. The digits to the left of the decimal point are whole seconds, and the digits to the right of the decimal point are parts of a second. You can see that with two digits to the right of the decimal point, we are measuring hundredths of a second. If you look at the two swimmers' times for this race and compare the two decimals, you can see that we would have to compare the hundredths place in order to determine the winner—all of the other digits are the same! You'll see that Michael Phelps won this race by *one hundredth* of a second!

See the race for yourself: http://www.youtube.com/watch?v=E3paiELa7mA

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Test your knowledge of decimal comparison by playing these games! The first is called Fruit Shoot and consists of three levels; the second is based on the classic Asteroids arcade game.

http://www.sheppardsoftware.com/mathgames/decimals/CompareDecimals.htm

http://themathgames.com/our-games/decimal-games/place-value/decimal-place-value-math-game