Step 1:
The first step to converting 665260.8399359 to a fraction is to re-write 665260.8399359 in the form p/q where p and q are both positive integers. To start with, 665260.8399359 can be written as simply 665260.8399359/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 665260.8399359, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 665260.8399359/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 665260.8399359/1 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 665260.8399359 as a fraction:
665261/1 / 1