Step 1:
The first step to converting 5406.90913921 to a fraction is to re-write 5406.90913921 in the form p/q where p and q are both positive integers. To start with, 5406.90913921 can be written as simply 5406.90913921/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 5406.90913921, which in this case is 8. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 5406.90913921/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 5406.90913921/1 each by 100000000:
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 5406.90913921 as a fraction:
59476/11 / 1