Step 1:
The first step to converting 42123.408621489 to a fraction is to re-write 42123.408621489 in the form p/q where p and q are both positive integers. To start with, 42123.408621489 can be written as simply 42123.408621489/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 42123.408621489, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 42123.408621489/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 42123.408621489/1 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 42123.408621489 as a fraction:
210617/5 / 1