Step 1:
The first step to converting 640597.9665911 to a fraction is to re-write 640597.9665911 in the form p/q where p and q are both positive integers. To start with, 640597.9665911 can be written as simply 640597.9665911/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 640597.9665911, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 640597.9665911/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 640597.9665911/1 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 640597.9665911 as a fraction:
640598/1 / 1