# Electronics and Communication Engineering - Digital Electronics - Discussion

22.

The greatest negative number which can be stored is 8 bit computer using 2's complement arithmetic is

 [A]. - 256 [B]. - 128 [C]. - 255 [D]. - 127

Explanation:

The largest negative number is 1000 0000 = -128.

 Geetha Adainjan said: (Jul 1, 2015) Why 1111 1111= -255 not came here? Please clarify it.

 Pratik said: (Jul 29, 2015) It is not largest number.

 Rekha.V said: (Aug 21, 2015) The greatest negative number which you can represent using N bit (of course signed) could be -2^(N-1). So for 8 bit 2^7 = -128.

 Rekha.V said: (Aug 21, 2015) The greatest negative number which you can represent using N bit (of course signed) could be -2^(N-1). So for 8 bit 2^7 = -128.

 Sudipta Majumder said: (Sep 16, 2015) Greatest positive number = 01111111. Taking 2's complement to get greatest negative number that is = 10000001. Now put the formula and we get = -127.

 Sunanda said: (Mar 19, 2017) Greatest positive number is 255, right?

 Sandy said: (Mar 24, 2017) No, the largest positive no is 127. 132,64,32,16,8,4,2,1. 0 1 1 1 1 1 1 1.

 Shubham said: (Aug 12, 2017) For 2's compliment. The range is -(2^n-1) to +((2^n-1)-1) and this is different in the case of 1's and signed representation.

 Divyesh Makwana said: (Feb 27, 2018) The largest Negative number in 8 bit is 01111111 and 2's complement of it in 10000000 which is -127.

 Pavan said: (Jun 25, 2018) In 8bit, 11111111 is the largest right?

 Pavan said: (Jun 25, 2018) And why 0111111 is largest? please explain.

 Dhanya said: (Jul 30, 2018) For 2's compliment representation, Range is {-2^(n-1) ) to +(2^(n -1))-1}. Here n=8 ,then { (-2^(8-1)) to +(2^(8-1))-1}. -2^7 to +(2^7)-1. -128 to +127. So, the greatest negative number in 2'compliment representation is - 128.

 Dhanya said: (Jul 30, 2018) -128 in 2's compliment form = 2's compliment of + 128. +128 in binary form=01111111. 2's compliment of 01111111=10000001.

 Sumesh said: (Jul 30, 2018) +128 = 10000000, -128 =2's compliment of 10000000, =1's compliment of 10000000 +1, = 01111111 +1, =1000000.

 Tshering Dorji said: (Jan 1, 2021) Then, what is the way to find the largest negative and positive number for 1s complement and signed number? Please, anyone, tell me.

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