Powers of 2 are important to understand and memorize for use with IP subnetting. To review powers of 2, remember that when you see a number with another number to its upper right (called an exponent), this means you should multiply the number by itself as many times as the upper number specifies. For example, 2 power of 3 is 2 × 2 × 2, which equals 8. Here’s a list of powers of 2 that you should commit to memory:
2 power of 1 = 2
2 power of 2 = 4
2 power of 3 = 8
2 power of 4 = 16
2 power of 5 = 32
2 power of 6 = 64
2 power of 7 = 128
2 power of 8 = 256
2 power of 9 = 512
2 power of 10 = 1,024
2 power of 11 = 2,048
2 power of 12 = 4,096
2 power of 13 = 8,192
2 power of 14 = 16,384
Before you get stressed out about knowing all these exponents, remember that it’s helpful to know them, but it’s not absolutely necessary. Here’s a little trick since you’re working with 2s: each successive power of 2 is double the previous one. For example, all you have to do to remember the value of 2 power of 9 is to first know that 2 power of 8 = 256. Why? Because when you double 2 to the eighth power (256), you get 2 power of 9 (or 512). To determine the value of 2 power of 10 , simply start at 2 power of 8 = 256, and then double it twice.
You can go the other way as well. If you needed to know what 2 power of 6 is, you just cut 256 in half two times: once to reach 2 power of 7 and then one more time to reach 2 power of 6.
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