Step 1:
The first step to converting 21057.399630507 to a fraction is to re-write 21057.399630507 in the form p/q where p and q are both positive integers. To start with, 21057.399630507 can be written as simply 21057.399630507/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 21057.399630507, which in this case is 9. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 21057.399630507/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 21057.399630507/1 each by 1000000000:
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 21057.399630507 as a fraction:
105287/5 / 1