# Logarithms

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Definition of a Logarithm:

If y = bx, then the logarithm, to the base b of a positive number is denoted by logb y and is defined by logb y = x.

And so, if 9 = 32, then the logarithm to the base 3 of 9 is defined by log3 9 = 2.

DON’T BE INTIMIDATED BY LOGARITHMS! ! ! Use this flashcard drill to become a master of logarithm basics.

CLICK HERE TO PRACTICE LOGS WITH VARIABLES

• log2 2 =
1
• log2 4 =
2
• log2 8 =
3
• log2 16 =
4
• log2 32 =
5
• log2 64 =
6
• log2 128 =
7
• log2 256 =
8
• log2 512 =
9
• log2 1024 =
10
• log3 9 =
2
• log3 27 =
3
• log3 81 =
4
• log3 243 =
5
• log3 729 =
6
• log3 2,187 =
7
• log4 16 =
2
• log4 64 =
3
• log4 256 =
4
• log4 1024 =
5
• log5 25 =
2
• log5 125 =
3
• log5 625 =
4
• log5 3,125 =
5
• log2 (1/4) =
-2
• log2 (1/8) =
-3
• log2 (1/16) =
-4
• log2 (1/32) =
-5
• log3 (1/9) =
-2
• log3 (1/27) =
-3
• log3 (1/81) =
-4
• log3 (1/243) =
-5
• log4 (1/16) =
-2
• log5 (1/25) =
-2

Use the form below to ask Fred more questions about logarithms.