here is my solution.
However, I would like to check some points in order to see if what I have done is acceptable or not. I didn't use the regex tool, however, I used the expression regex_replace to get the same result on exercise 2. is that ok?
Same for exercise 3.
about exercise 4, I tried different methods to write just one expression that could attend all the conditions, but I didn't get it, so in my formula tool, there are 3 formulas inside. Is that ok?
Do I need to follow any specific rules or criteria, or does it not matter how it is counted as long as I receive the same answer?
