21 in Binary = 10101
Binary Representation
10101
Decimal 21 = 10101 (binary)
21 in All Number Bases
Decimal
21
Binary
10101
Octal
25
Hexadecimal
15
How to Convert 21 to Binary
- Divide 21 by 2, record the remainder
- Continue dividing the quotient by 2
- Read the remainders from bottom to top
- Result: 10101
Try the Number Base Converter
Conversions
Binary (2)
0b10101
Octal (8)
0o25
Decimal (10)
21
Hexadecimal (16)
0x15
Binary Bits
0
0
0
1
0
1
0
1
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 |
| 8 | 1000 | 10 | 8 |
| 10 | 1010 | 12 | A |
| 16 | 10000 | 20 | 10 |
| 32 | 100000 | 40 | 20 |
| 64 | 1000000 | 100 | 40 |
| 127 | 1111111 | 177 | 7F |
| 128 | 10000000 | 200 | 80 |
| 255 | 11111111 | 377 | FF |