Step 1:
The first step to converting 1663643797.6851 to a fraction is to re-write 1663643797.6851 in the form p/q where p and q are both positive integers. To start with, 1663643797.6851 can be written as simply 1663643797.6851/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 1663643797.6851, which in this case is 4. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 1663643797.6851/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 1663643797.6851/1 each by 10000:
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 1663643797.6851 as a fraction:
1663643797/1 / 1