Step 1:
The first step to converting 78642.400429818 to a fraction is to re-write 78642.400429818 in the form p/q where p and q are both positive integers. To start with, 78642.400429818 can be written as simply 78642.400429818/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 78642.400429818, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 78642.400429818/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 78642.400429818/1 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 78642.400429818 as a fraction:
393212/5 / 1