Step 1:
The first step to converting 639584.6786079 to a fraction is to re-write 639584.6786079 in the form p/q where p and q are both positive integers. To start with, 639584.6786079 can be written as simply 639584.6786079/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 639584.6786079, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 639584.6786079/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 639584.6786079/1 each by 10000000:
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 639584.6786079 as a fraction:
639585/1 / 1