Step 1:
The first step to converting 398123.9427381 to a fraction is to re-write 398123.9427381 in the form p/q where p and q are both positive integers. To start with, 398123.9427381 can be written as simply 398123.9427381/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 398123.9427381, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 398123.9427381/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 398123.9427381/1 each by 10000000:
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 398123.9427381 as a fraction:
398124/1 / 1