1.1 · Lesson 6 of 6
Negative binary numbers
Syllabus 1.1.6
What this lesson covers
- Represent positive and negative integers in 8-bit two's complement
Key vocabulary
- Two's complement
- A way of representing negative and positive integers in binary. To make a number negative, flip the bits and add 1.
- Sign bit
- The leftmost bit in two's complement: 1 means negative and 0 means positive.
- Add 1
- The second step of two's complement: after flipping the bits, add 1 using binary addition.
- Flip the bits
- Change every 0 to 1 and every 1 to 0. Followed by adding 1, it changes a number's sign.
- Range
- The smallest to largest values that can be stored. 8-bit two's complement is −128 to 127.
- Sign and magnitude
- Another way to show negative binary numbers, where the MSB is just a + or − sign. It has flaws, so two's complement is used instead.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 6 terms
- Activity 1: Positive denary → negative binary · 8 questions
- Activity 2: Negative denary → binary · 8 questions
- Activity 3: Positive ↔ negative binary · 8 questions
- Activity 4: Two's complement → denary · 8 questions