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  1. If log 2 = 0.30103, log 3 = 0.47712, the number of digits in 620 is

  2. A.
    8
    B.
    12
    C.
    16
    D.
    20

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    Answer : Option C

    Explanation :

    We have to take 620 with log
    We know that log mn = n log m
    Now, log 620 = 20 log 6
    Or, 20 log (2*3)
    We know that log (m*n) = log m + log n
    Now, 20 [log 2 + log 3] = 20 [0.30103 + 0.47712] = 20 [0.77815]
    Since, the number of digits in 620 = 15.563, round up value = 16
    Therefore the number of digits = 16


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