Step 1:
The first step to converting 39991.900618122 to a fraction is to re-write 39991.900618122 in the form p/q where p and q are both positive integers. To start with, 39991.900618122 can be written as simply 39991.900618122/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 39991.900618122, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 39991.900618122/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 39991.900618122/1 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 39991.900618122 as a fraction:
399919/10 / 1