Originally Posted by

**gary223** Assuming a 8-Bit number system, use the 2's complement method to perform the following arithemetic. Verify your anwsers, showing all workings.

$\displaystyle 113_{10}$

-$\displaystyle 98_{10}$

...

Hello,

I assume that you know how to convert a number of decimal system in a binary number. Code:

113 =======> 01110001 [a]
10
98 =======> 01100010 [b]
10
-98 =======> 10011101 [c]
10
+ 00000001 [d]
----------------------------
1|00001111 [e]

[a] 113 converted into binary number

[b] 98 converted into binary number

[c] change every digit. The first digit correspond to the sign: 0 means +, 1 means -.

[d] add 1

[e] now add [a], [c],[d]. You have to use a carry-bit which is always set to 1 if the sum of three digits is 2 or 3.

[e] the result are the **last 8 digits**

Convert the dual number 00001111 ==> 15

Seems to be the right result.