Step 1:
The first step to converting 354.2099973 to a fraction is to re-write 354.2099973 in the form p/q where p and q are both positive integers. To start with, 354.2099973 can be written as simply 354.2099973/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 354.2099973, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 354.2099973/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 354.2099973/1 each by 10000000:
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 354.2099973 as a fraction:
28691/81 / 1