Lesson
Multiplying by "Powers of Ten"
Have you ever noticed that multiplying by 10 can seem pretty easy? 3 x 10 = 30 12 x 10 = 120 Do you see what happens? Every time we multiply a number by 10, we simply add a zero to the end of the first factor, and you have your product! It turns out that it is also easy to multiply by all of the members of the ten family: x 100 x 1,000 x 10,000 x 100,000 ...and so on. We call these ten family numbers THE POWERS OF TEN. Don't worry, they aren't as scary as they seem :) The secret to this Math Skill #5 is to count the number of zeroes in the tens family factor, and then add that same number of zeroes to the other factor. For example: 4 x 10,000 = 40,000 Since there are four zeros in the number 10,000, we simply add those to the end of the 4, and we get 40,000 for our product. Here's another: 170 x 100 = 17,000 Since there are two zeros in 100, we add those zeros to the end of 170, and we get a product of 17,000. 
Using Exponents to show the Powers of Ten
In Math, we have these cool symbols called "exponents" to help us write large numbers like 1,000,000 a little more efficiently. You have probably seen these tiny numbers on the corner of numbers before: The exponent is the tiny red number above the ten above. It tells you how many times to multiply the number ten. For example, 10 to the power of two (above) is the same as 10 x 10, which equals 100.
You will use these exponents to help you organize complex and long numbers in middle school, high school and beyond! 
Video LEssons
Multiplying by Powers of 10.

Math Antics Video on Using Exponents

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