Quickly Convert Binary to Decimal in Your Head

1. Start at the first ‘1′ on the left, and start with the mental number one2. Move one digit right. If that digit is a zero, multiply your mental number by two. If it is a one,

multiply your mental number by two and add one.3. Repeat step 2 for every digit of the binary number

Example: 1011010:

1011010 – We start at the first one. Our mental total: 1 1011010 – Next digit is a zero; we double our mental number: 1 x 2 = 2. 1011010 – Next digit is a one; we double our mental number and add one: 2 x 2 + 1 = 5 1011010 – Another one; double and add one: 5 x 2 + 1 = 11 1011010 – Zero; double: 11 x 2 = 22 1011010 – One; double and add one: 22 x 2 + 1 = 45 1011010 – And finally a zero; double: 45 x 2 = 90

Quickly Convert Decimal to Binary in Your Head???????

1. Start with the decimal number in your head2. Is the current decimal number divisible by 2?

a. Yes, write down 0b. No, write down 1 and subtract 1 from the mental number.

3. Divide your mental number by 2 and go back to step 2. Repeat until your mental number is 0.

Example: 90:

90 – 0 45 – 1 44 – 0 22 – 0 11 – 1 10 – 0 5 – 1 4 – 0 2 – 0 1 – 1 0