15 = 1111 · 4 bits · octal 17 · hex F
15 in binary
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the answer
15 in binary is 1111 (4 bits).
the answer
15 in binary is 1111
1510 = 11112. Also 17 in octal (base 8) and F in hexadecimal (base 16).
repeated division
Method: divide by 2 and keep the remainders
| Divide | Quotient | Remainder |
|---|---|---|
| 15 | 7 | 1 |
| 7 | 3 | 1 |
| 3 | 1 | 1 |
| 1 | 0 | 1 |
Read the remainders from the bottom up: 1111.
place value
Check it: binary place values
| Place | Digit | Value |
|---|---|---|
| 8 | 1 | 8 |
| 4 | 1 | 4 |
| 2 | 1 | 2 |
| 1 | 1 | 1 |
8 + 4 + 2 + 1 = 15.
neighbours
Nearby numbers in binary
| Decimal | Binary |
|---|---|
| 14 | 1110 |
| 15 | 1111 |
| 16 | 10000 |
| 30 | 11110 |
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The answer appears here, with the working in words.
practice
✏️ Five questions, answers hidden
1. Write 16 in binary.
Answer: 10000
2. Write 30 in binary.
Answer: 11110
3. Convert 10010 to decimal.
Answer: 18
4. Write 255 in binary.
Answer: 11111111
5. Write 15 in octal.
Answer: 17
where this is taught
📚 The class this belongs to
Binary numbers are taught in middle-school maths and in computing (KS3 computing in the UK, AP Computer Science Principles in the US, Class 11 Computer Science in CBSE).
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related
🔗 Nearby numbers and topics
The maths library, by topic
Questions
Asked about 15 in binary
1What is 15 in binary?
1111. Divide by 2 repeatedly and read the remainders upwards.
2How many bits does 15 need?
4 bits: the largest power of 2 not above 15 is 8.
3What is 1111 in decimal?
15: 8 + 4 + 2 + 1.
4What is 15 in hexadecimal?
F. Group the binary digits in fours from the right; each group is one hex digit.