10 questions🇬🇧English
💾 Two's Complement & Floating Point – A-level
Computer Science · A-level — practises negative binary numbers, fixed point, floating point and normalisation
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Questions
What is the range of integers that can be stored in 8-bit two's complement?
−128 to +127
−128 to +128
−127 to +127
0 to 255
20s
What is the denary value of the 8-bit two's complement number 11111111?
−1
−128
−127
255
20s
Which is −20 written in 8-bit two's complement?
11101100
11101011
01101100
10010100
30s
An unsigned fixed-point number has 4 bits before and 4 bits after the binary point. What is 0110.1010 in denary?
6.75
6.5
6.10
6.625
30s
Using 8-bit two's complement, what is 00110010 − 00010111?
11100101
00011011
00011101
01001001
60s
Which of these two's complement mantissas is normalised?
0.1011000
0.0011010
1.1010000
0.0101100
30s
In 8-bit two's complement, 01110000 + 01000000 gives 10110000. What has happened?
Overflow: the true sum is above +127
A rounding error in the lowest bit
No error: the answer is −80
Underflow: the true sum is below −128
30s
A floating-point number has mantissa 1.0110000 and exponent 0010, both in two's complement. What denary value is stored?
−2.5
−0.625
−5
−1.5
60s
With a fixed total number of bits, more bits go to the mantissa and fewer to the exponent. What is the effect?
Greater range but less precision
Smaller range and less precision
Greater precision and greater range
Greater precision but smaller range
30s
A floating-point result is non-zero but too close to zero for the format to represent. What is this called?
Overflow
Truncation
Normalisation
Underflow
20s