Step 1:
The first step to converting 16581.639751989 to a fraction is to re-write 16581.639751989 in the form p/q where p and q are both positive integers. To start with, 16581.639751989 can be written as simply 16581.639751989/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 16581.639751989, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 16581.639751989/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 16581.639751989/1 each by 1000000000:
Step 3:
Now the last step is to simplify the fraction (if possible) by finding similar factors and cancelling them out, which leads to the following answer for 16581.639751989 as a fraction:
182398/11 / 1