Step 1:
The first step to converting 509406.36407879 to a fraction is to re-write 509406.36407879 in the form p/q where p and q are both positive integers. To start with, 509406.36407879 can be written as simply 509406.36407879/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 509406.36407879, which in this case is 8. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 509406.36407879/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 509406.36407879/1 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 509406.36407879 as a fraction:
509406/1 / 1