No.
No.
Oh, dude, renaming the fractional sum when adding mixed numbers is like wearing a hat indoors - it's not necessary, but it might make things a bit fancier. Technically, you can add mixed numbers without renaming the sum, but it can make the math simpler and easier to understand. So, like, you do you - rename or not, it's all good.
rename 8/1 as a whole number
If you can do it without, go ahead. But it helps to get the correct answer, since three is larger than one. If you re-name 4 and 1/4 to 3 and 5/4, it's easier to subtract 3/4 from it.
It is still a subtraction problem.
When adding or subtracting fractions with different denominators their lowest common denominator must be found first by using the LCM of their denominators
Probably not, but it depends on what you mean by "3th".
prime numbers, yes
You rename a directory the same way you rename a file. Use the 'mv' command to rename it.
When doing sums with mixed numbers, it is often easier to convert the mixed numbers to improper fractions, do the sum and convert any resulting improper fraction back to a mixed number. This is especially true of division, but with subtraction, if the fraction part of the second mixed number is larger than the fraction part of the first mixed number (subtracting the second from the first), this will result in requiring borrowing from the whole number of the first mixed number. Using improper fractions avoids this complication and makes all sums easier.
No, you would have to make the code.
Because you cannot subtract 3/4 from 1/4.