A computer uses 8 digit mantissa and 2 digit exponent. If a = 0.052 and b =…

2008

A computer uses 8 digit mantissa and 2 digit exponent. If a = 0.052 and b = 28E + 11 then b + a - b will

  1. A.

    result in an overflow error

  2. B.

    result in an underflow error

  3. C.

    be 0

  4. D.

    be 5.28 E + 11

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Correct answer: C

Floating-point arithmetic uses a fixed number of digits for the mantissa (8 in this case). When adding numbers with vastly different magnitudes, alignment shifts the smaller mantissa. Here, b (28E + 11) is significantly larger than a (0.052), creating an exponent difference of roughly 13 orders of magnitude. Since the precision (8 digits) is insufficient to represent a when aligned with b, adding them results in no change due to rounding (absorption). Therefore, subtracting b subsequently yields exactly zero.

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