Step 1:
The first step to converting 645599.9959843 to a fraction is to re-write 645599.9959843 in the form p/q where p and q are both positive integers. To start with, 645599.9959843 can be written as simply 645599.9959843/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 645599.9959843, which in this case is 7. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 645599.9959843/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 645599.9959843/1 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 645599.9959843 as a fraction:
645600/1 / 1