Orders of Magnitude

Key Questions

  • The mathematical explanation is to take the base ten log of a number and floor it, however, that's just a fancy math way of saying count the digits before the decimal marker then take 1.

  • Answer:

    It depends on what you mean by "order of magnitude".

    Explanation:

    In one meaning, it is a number's nearest power of 10.

    For example, #9.9 × 10^2# is much closer to #10^3# than to #10^2#, so we say that the order of magnitude is #3#.

    By the same argument, #9.9 × 10^-3# is closer to #10^-2# than to #10^-3#, so we say that the order is #-3#.

    In another meaning, it is a difference of #1# unit in the exponent of #10# in the value of a quantity.

    Thus, #2315# is one order of magnitude larger than #231.5#, and #23.15# is one order of magnitude less than #231.5#.

    If the value of a number decreased from #2315# to #23.15#, we would say that it decreased by two orders of magnitude or that the values differed by two orders of magnitude.

    In that sense, a difference in orders of magnitude is always expressed as a positive number.

Questions