EECS 1520 Lecture Notes - Lecture 4: Negative Number

• School: York University
• Department: Electrical Engineering and Computer Science
• Course: EECS 1520
• Professor: Steven Castellucci

Document Summary

3. 2 /continued equals +42 equals 42 equals -10 equals 90 equals -10 equals 90. 80 plus 30 equals +10 equals 10 (110) Subtraction reduces to addition because a b = a + ( b) Easy to convert a positive number to its negative counterpart, and a negative number to its positive counterpart. Used in computers because subtraction reduces to addition. Start with the positive version of the number. Flip the bits: 0 1 and 1 0. Add 1 to the number produced in the previous step in both directions. The above steps are an indirect way of carrying out the evaluation of 2n - x , namely x [(2n 1) x] + 1. Note: same process will convert between positive and negative representations, 24 x = 24 5 = 16 5 = 11 in binary this is. Now add one to this result. (24 1) x = (24 1) 5 = 10 in binary this is.