Step 1:
The first step to converting 872.21163545768 to a fraction is to re-write 872.21163545768 in the form p/q where p and q are both positive integers. To start with, 872.21163545768 can be written as simply 872.21163545768/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 872.21163545768, which in this case is 11. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 872.21163545768/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 872.21163545768/1 each by 100000000000:
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 872.21163545768 as a fraction:
28783/33 / 1