Step 1:
The first step to converting 3129.138216121 to a fraction is to re-write 3129.138216121 in the form p/q where p and q are both positive integers. To start with, 3129.138216121 can be written as simply 3129.138216121/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 3129.138216121, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 3129.138216121/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 3129.138216121/1 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 3129.138216121 as a fraction:
90745/29 / 1