21 Ternary to Binary
21 ternary = 111 binary
21 written in binary is 111, the number 7 in everyday decimal.
21 ternary = 111 binary
How to convert 21 to binary
Step 1: Ternary to decimal
Multiply each digit by 3 to the power of its position (0 on the right), then add:
| Digit | Place value | Digit × place |
|---|---|---|
2 | 31 = 3 | 6 |
1 | 30 = 1 | 1 |
6 + 1 = 7
Step 2: Decimal to binary
Divide by 2 repeatedly and keep the remainders. Reading the remainders from the last one to the first gives the binary digits:
| Division | Quotient | Remainder (digit) |
|---|---|---|
| 7 ÷ 2 | 3 | 1 |
| 3 ÷ 2 | 1 | 1 |
| 1 ÷ 2 | 0 | 1 |
Result: 7 = 111 in binary.
21 (ternary) in other systems
| Decimal | 7 |
| Roman numerals | VII |
| Hexadecimal | 7 |
| Octal | 7 |
| Duodecimal | 7 |
| Base 36 | 7 |
| Vigesimal | 7 |
| Quaternary | 13 |
| Quinary | 12 |
| Senary | 11 |
Nearby ternary to binary conversions
| 2 to binary | 10 |
| 10 to binary | 11 |
| 11 to binary | 100 |
| 12 to binary | 101 |
| 20 to binary | 110 |
| 22 to binary | 1000 |
| 100 to binary | 1001 |
| 101 to binary | 1010 |
| 102 to binary | 1011 |
| 110 to binary | 1100 |
About the number 7
- 7 is an odd number.
- 7 is a prime number.
- Written in binary it needs 3 bits, so it fits in one byte.
Reverse conversion
Frequently asked questions
What is 21 in binary?
21 in ternary is 111 in binary (the number 7 in decimal).