中四電腦科的計數題

〖01001011〗_2 - 〖00100111〗_2 in computer you can’t do…
so that is why 2's complement come in...
Give you example…..例如
〖01001011〗_2 + 〖00100111〗_2 --- make 〖00100111〗_2 2nd complement
(75)+(-39)= 36
(1st complement- 反) 00100111 = 11011000
(2nd complement- +1) 11011000+1 = 11011001
01001011 + 11011001 = 100100100 -> now we have 9 bits, so we ignore the MSB(most significant bit)因為超bit,要ignore
= 00100100 to decimal = 36 done!

太複習同睇唔明,OK