Step 1:
The first step to converting 120400.129112 to a fraction is to re-write 120400.129112 in the form p/q where p and q are both positive integers. To start with, 120400.129112 can be written as simply 120400.129112/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 120400.129112, which in this case is 6. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 120400.129112/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 120400.129112/1 each by 1000000:
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 120400.129112 as a fraction:
842801/7 / 1