Step 1:
The first step to converting 6403.987622424 to a fraction is to re-write 6403.987622424 in the form p/q where p and q are both positive integers. To start with, 6403.987622424 can be written as simply 6403.987622424/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 6403.987622424, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 6403.987622424/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 6403.987622424/1 each by 1000000000:
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 6403.987622424 as a fraction:
512319/80 / 1