Convert 01010001 from binary to decimal

Each digit in binary has a different value, very much the same as the way the three in 32 has a different value than the three in 321. Whereas this goes from 30 to 300, and you multiply by 10 every time, in binary we multiply by 2 every time instead. This means the right most digit has a value of 1, the next 2, the next 4, and you keep multiplying by 2 until you get to the end of the sequence of numbers. Once we know how much each one is worth, every time we see a '1', we add this number to our total, starting from the right! So for our example we would do 1+16+64 = 81. This means 01010001 represents 81 in binary.