CMA Foundation · Fundamentals of Business Mathematics and Statistics · Indices and Logarithms
If log 6.4 = 0.8062, what is the logarithm of 0.0064 written as characteristic and mantissa?
The logarithm is 3̄.8062, meaning minus 3 plus 0.8062. Because 0.0064 equals 6.4 times 10 to the power minus 3, the characteristic is -3 while the mantissa remains the positive 0.8062, the same as for 6.4.
- A3̄.8062 (that is, -3 + 0.8062)Correct
- B2̄.8062 (that is, -2 + 0.8062)
- C3.8062
- D-3.8062
Explanation
0.0064 = 6.4 × 10^-3, so log 0.0064 = -3 + 0.8062 = 3̄.8062. The mantissa stays positive. Option -3.8062 is wrong because it makes the mantissa negative, which equals -3 - 0.8062, a different number.
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