Question

In the binary number system, the number $100$ represents

• A. one
• B. three
• C. four
• D. hundred

Answer 1

The correct option is C four

In binary number system only $0$'s and $1$'s are used to built the whole number system.
Hence,
$0=0$
$1=1$
Start back at $0$ again, but add $1$ on the left,
$2=10$
$3=11$
Start back at $0$ again, and add one to the number on the left, but that number is already at $1$, so it also goes back to $0$ and $1$ is added to the next position on the left. Hence,
$4=100$ .... and so on.