Step 1:
The first step to converting 53.421240172009 to a fraction is to re-write 53.421240172009 in the form p/q where p and q are both positive integers. To start with, 53.421240172009 can be written as simply 53.421240172009/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 53.421240172009, which in this case is 12. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 53.421240172009/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 53.421240172009/1 each by 1000000000000:
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 53.421240172009 as a fraction:
14584/273 / 1