4.5.4.9 Underflow and overflow Quiz: AQA Computer Science, Unit 5

The 20 questions

1. What condition occurs when a calculation produces a value too large to be stored?

   • Underflow
   • Rounding error
   • Overflow
   • Truncation

2. What occurs when a calculated result's magnitude is too small to be represented?

   • Underflow
   • Rounding error
   • Overflow
   • Truncation

3. In floating point representation, what condition directly causes underflow to occur?

   • Sign bit inversion
   • Mantissa too large
   • Exponent too large
   • Exponent too small

4. In unsigned integer addition, when does arithmetic overflow occur?

   • Sum exceeds maximum
   • Sum becomes negative
   • Result is fractional
   • Sum equals zero

5. What happens when adding two positive numbers exceeds the maximum two's complement value?

   • Zero result produced
   • Negative result produced
   • Positive result doubled
   • Underflow error produced

6. Which numerical outcome describes floating point underflow?

   • Loss of sign bit
   • Result exceeds maximum
   • Division by zero error
   • Result rounded to zero

7. What occurs when adding 1 to 255 in 8-bit unsigned binary?

   • Arithmetic overflow
   • Quantisation error
   • Arithmetic underflow
   • Rounding error

8. Why does calculating 9 + 8 cause an overflow in 4-bit unsigned binary?

   • Maximum limit 15
   • Maximum limit 7
   • Maximum limit 31
   • Maximum limit 16

9. A format's smallest positive value is 10^-38. What happens when storing 10^-41?

   • Stored without error
   • Underflows to zero
   • Overflows to infinity
   • Wraps to negative

10. What decimal value is stored when 1 is added to 0111 in 4-bit two's complement?

    • 0
    • -8
    • 8
    • -7

11. What is the 4-bit unsigned result when subtracting 5 from 3?

    • 14
    • -2
    • 2
    • 0

12. A floating point exponent is too large to store in its field. What is this error called?

    • Overflow
    • Normalisation
    • Underflow
    • Rounding error

13. What decimal value is stored when 1 is added to 127 in 8-bit two's complement?

    • 128
    • 0
    • -128
    • -1

14. What happens when 64 and 63 are added using 8-bit unsigned binary?

    • Stored correctly
    • Unsigned overflow occurs
    • Underflow occurs
    • Wraps to negative

15. How is overflow detected in n-bit unsigned binary addition?

    • MSB sign change
    • Zero flag set
    • MSB carry out
    • Parity bit change

16. Adding two positive two's complement numbers overflows if the result has which property?

    • Negative sign bit
    • Even parity
    • Positive sign bit
    • Zero sign bit

17. What primary issue do both rounding errors and underflow cause in calculations?

    • Hardware damage
    • Memory corruption
    • Infinite loops
    • Loss of precision

18. An 8-bit unsigned register contains 254 and increments by 3. What decimal value is stored?

    • 257
    • 0
    • 2
    • 1

19. What occurs when a calculated number is too small to be represented in floating-point format?

    • Truncation
    • Overflow
    • Underflow
    • Normalisation

20. What error occurs when a calculation produces a result too large for the allocated bits?

    • Syntax error
    • Underflow
    • Parity error
    • Overflow

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