Step 1:
The first step to converting 3120.345 to a fraction is to re-write 3120.345 in the form p/q where p and q are both positive integers. To start with, 3120.345 can be written as simply 3120.345/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 3120.345, which in this case is 3. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 3120.345/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 3120.345/1 each by 1000:
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 3120.345 as a fraction:
81129/26 / 1