Step 1:
The first step to converting 639571.5405912 to a fraction is to re-write 639571.5405912 in the form p/q where p and q are both positive integers. To start with, 639571.5405912 can be written as simply 639571.5405912/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 639571.5405912, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 639571.5405912/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 639571.5405912/1 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 639571.5405912 as a fraction:
639571/1 / 1