Binary Decimal Hexadecimal Conversions
Binary
Decimal Hexadecimal 
log based 2
log based 10 log based 16 
0, 1
0, 1, 2, 3, 4, 5, 6, 7, 8, 9 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F 
For hexadecimal to decimal system:

A = 10
B = 11 C = 12 D = 13 E = 14 F = 15 
How to do the conversion below
If you multiply each digit to the proper position (I color coded them), you will get the decimal.
Since F = 15, this hexdecimal number is equivalent to the following decimal.
(15 * 16^5) + (15 * 16^4) + (15 * 16^3) + (15 * 16^2) + (15 * 16^1) + (15 * 16^0)
Let's take a look at Binary to Decimal conversions
Since F = 15, this hexdecimal number is equivalent to the following decimal.
(15 * 16^5) + (15 * 16^4) + (15 * 16^3) + (15 * 16^2) + (15 * 16^1) + (15 * 16^0)
Let's take a look at Binary to Decimal conversions
Binaries consists of 0s and 1s with log based 2.
Let's try converting 1010101 instead.
2^6 + 2^4 + 2^2 + 2^0 = 64 + 16 + 4 + 1 = 85
Let's try converting 1010101 instead.
2^6 + 2^4 + 2^2 + 2^0 = 64 + 16 + 4 + 1 = 85