Step 1:
The first step to converting 21643.45945721 to a fraction is to re-write 21643.45945721 in the form p/q where p and q are both positive integers. To start with, 21643.45945721 can be written as simply 21643.45945721/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 21643.45945721, which in this case is 8. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 21643.45945721/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 21643.45945721/1 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 21643.45945721 as a fraction:
238078/11 / 1