Question

What is the logarithmic form of 7^5=16,807?

Answer 1

To go from exponential to logarithmic, you can use $e^x=y$ (exponential) => $log_{e} (y)=x$ (logarithmic). With your specific equation, this would make $7^5=16,807$ => $log_7(16,807)=5$, with that being your logarithmic form.

Answer 2

The last digit (1s place; just to the left of the decimal dot) recurs after the power is 4+.
7⁰⁺⁴ⁿ all have the last digit as '1'.
7¹⁺⁴ⁿ have the last digit as '7'.
7²⁺⁴ⁿ have the last digit as '9'.
7³⁺⁴ⁿ have the last digit as '3'.
7⁴⁺⁴ⁿ, the same as 7⁰⁺⁴ⁿ have the last digit as '1'.
replace the 7 with 16 in the expression. 807