Step 1:
The first step to converting 3991405.164119 to a fraction is to re-write 3991405.164119 in the form p/q where p and q are both positive integers. To start with, 3991405.164119 can be written as simply 3991405.164119/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 3991405.164119, which in this case is 6. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 3991405.164119/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 3991405.164119/1 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 3991405.164119 as a fraction:
3991405/1 / 1