A good answer might be:

32 bits.

Hex Addition

Here is a problem with 4 bits: 

1111
 0111
 1001
 ----
 0000 
Overflow was detected.

Two four-bit numbers are added, but the sum does not fit in four bits. If we were using five bits the sum would be 1 0000. But with four bits there is no room for the significant "1". Because the carry out from the most significant column of the sum (the left column) is "1", the 4-bit result is not valid.

The electronic circuits of a computer can easily detect overflow by checking if the carry-out of the leftmost column is a zero or a one. A program might branch to an error handling routine when overflow is detected.

QUESTION 6:

Add these numbers, represented in eight bits: 

     
0010 1100
0101 0101
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