Step 1:
The first step to converting 690.6639922121 to a fraction is to re-write 690.6639922121 in the form p/q where p and q are both positive integers. To start with, 690.6639922121 can be written as simply 690.6639922121/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 690.6639922121, which in this case is 10. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 690.6639922121/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 690.6639922121/1 each by 10000000000:
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 690.6639922121 as a fraction:
84261/122 / 1