Step 1:
The first step to converting 520.6420898438 to a fraction is to re-write 520.6420898438 in the form p/q where p and q are both positive integers. To start with, 520.6420898438 can be written as simply 520.6420898438/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 520.6420898438, which in this case is 10. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 520.6420898438/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 520.6420898438/1 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 520.6420898438 as a fraction:
42172/81 / 1