In binary, each digit to the left multiplies by 2. hover over the digit to see its value. click on the digit to turn it on. you can make 256 numbers, including zero. for a number bigger than 255, you need more digits. (8-bit, 16-bit, 32-bit, etc.) 8-bits are a byte.
to make a number, for example, 43, find the biggest number starting from the left that can fit. (32) then, subtract 32 from 43 (11 = 8 + 2 + 1) to make 42. turn on the 32, 8, 2, and 1 switch to get 43. any switch that is a zero is not counted. I'm self taught, so i might make mistakes.