Step 1:
The first step to converting 666598.21187998 to a fraction is to re-write 666598.21187998 in the form p/q where p and q are both positive integers. To start with, 666598.21187998 can be written as simply 666598.21187998/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 666598.21187998, which in this case is 8. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 666598.21187998/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 666598.21187998/1 each by 100000000:
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 666598.21187998 as a fraction:
666598/1 / 1