Step 1:
The first step to converting 39999.99879 to a fraction is to re-write 39999.99879 in the form p/q where p and q are both positive integers. To start with, 39999.99879 can be written as simply 39999.99879/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 39999.99879, which in this case is 5. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 39999.99879/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 39999.99879/1 each by 100000:
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 39999.99879 as a fraction:
40000/1 / 1