Grokking Algorithms: An illustrated guide for programmers and other curious people

by Aditya Y. Bhargava

You may not remember what logarithms are, but you probably know what exponentials are. log10 100 is like asking, “How many 10s do we multiply together to get 100?” The answer is 2: 10 × 10. So log10 100 = 2. Logs are the flip of exponentials.