9 in Binary
9 in binary is 1001. It takes 4 bits to write, and as a full byte it is 00001001.
How to convert 9 to binary
Divide by 2, write down the remainder, and repeat with the quotient until it reaches 0. The remainders, read from the last row up to the first, spell out 1001.
| Division | Quotient | Remainder |
|---|---|---|
| 9 ÷ 2 | 4 | 1 |
| 4 ÷ 2 | 2 | 0 |
| 2 ÷ 2 | 1 | 0 |
| 1 ÷ 2 | 0 | 1 |
Check it the other way
To verify, read 1001 left to right, giving each digit its place value and adding up the places that hold a 1.
| Bit | Place value | Contributes |
|---|---|---|
| 1 | 23 = 8 | 8 |
| 0 | 22 = 4 | 0 |
| 0 | 21 = 2 | 0 |
| 1 | 20 = 1 | 1 |
Adding the contributions: 8 + 0 + 0 + 1 = 9. The conversion checks out.
9 in every base
| Format | Value |
|---|---|
| Binary | 1001 |
| Decimal | 9 |
| Hexadecimal | 9 |
| Octal | 11 |
| As a byte (8-bit) | 00001001 |
Worth knowing about 9
Nine is the largest single-digit decimal number, yet in binary it already takes four digits, 1001, which happen to read the same in both directions.
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Nearby numbers
Or browse the full table at numbers in binary.
FAQ
What is 9 in binary?
9 in binary is 1001. Each digit's place is worth double the one to its right, starting from 1. Add up the places holding a 1 and you get 9 back. As a full 8-bit byte it is written 00001001, the same value padded with leading zeros.
How many bits does 9 need?
9 needs 4 bits in binary: 1001. A number needs one more bit each time it crosses a power of two, which is why the counts climb slowly. Stored in a computer it usually occupies a full 8-bit byte anyway, written 00001001 with zeros filling the front.
What is 9 in hex?
9 in hexadecimal is 9. Hex is base 16, so every hex digit stands for exactly four binary digits, which makes it a compact way to write the same value. In octal, base 8, 9 becomes 11. All three are just different spellings of the number 9.