Actually, there is something special about 10. We use base-10 numbers because we have ten fingers. There is also something special about the use of 2 as the basis for a number system. What is it? Given a decimal (base 10) or a ternary (base 3) number with k digits, a natural question is; how much information is included in this k-digit number? We answer this by determining the number of bits it takes to express the given number. Assuming that the answer is x, then 10k − 1 = 2x − 1. This is because 10k − 1 is the largest k-digit decimal number and 2x − 1 is the largest x-bit binary number. Solving the equation above for x as the unknown is easily done using logarithms and yields
x = K 
.