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Lesson 62: Exponential Notation
This lesson introduces the concept of exponents, which is very important because it comes up almost constantly in math. Make sure you understand them fully.
We know that multiplication is repeated addition. For example if we write 3 x 7, what we really mean is 3 + 3 + 3 + 3 + 3 + 3 + 3. We have something similar for repeated multiplication, and it's called exponential notation. Here is how it works.
If we want to multiply the number 2 five times, we can write 25. This would be read as "two to the power of five," or "two to the fifth.". It's just a shorter way of writing 2 x 2 x 2 x 2 x 2. The answer would be 32. The little 5 is called an exponent.
If we write 92, it means 9 x 9, which is 81. This would be read as "nine to the second power", or more commonly "nine squared."
If we write 43, it means 4 x 4 x 4, which is 64. This would be read as "four to the third (power)", or more commonly, "four cubed."
Note that a number to the power of 1 just equals itself. For example, 51 = 5. That's because we're not multiplying it by anything. It's just the number itself.
Powers of 10 are quite important, as you'll learn later. 102 = 100, 103 = 1000, etc.
Later you will have much more practice with exponents, and you'll learn many more rules for how to work with them.
Remember that you can ask a math question if you have additional questions about a topic, or you can contact me if you have any comments or suggestions for this site.