trjhtr

I'm learning Python for 2 months now and I'm working on a little exercise app calculating percentages. I'd like to ask for a code review and comments. I'd like to make sure I'm following the right habits from the beginning.

# coding: utf-8

# In[9]:


def percA(perc, num):
 perc_a = perc/100 * num
 return perc_a

def percB(first, second):
 percB = first/second*100
 return percB

def percC(old, new):
 percC = (new - old)/old*100
 return percC

def percD(num, perc):
 perc = perc/100
 percD = num * (1 + perc)
 return percD

def percE(num, perc):
 perc = perc/100
 percD = num * (1 - perc)
 return percD

print("**************************************")
print("************** WELCOME ***************")
print("**************************************")
print("n")
choose = input("Choose option:nA. X% of YnB. X is what percent of YnC. By what percentage a number increased?nD. Add percent to a numbernE.Substract percentage from a numbernYour answer: ")
if choose.isupper() == True:
 choose = choose.lower()
while choose == "a":
 if "a":
 usrperc = int(input("Provide percentage: "))
 usrnum = int(input("Provide number: "))
 result = percA(usrperc, usrnum)
 print("0% of 1 is 2".format(usrperc, usrnum, result))
 break
 elif "b":
 usrperc = int(input("Provide percentage: "))
 usrnum = int(input("Provide number: "))
 result = percA(usrperc, usrnum)
 print("0% of 1 is 2".format(usrperc, usrnum, result))
 break
else:
 print("Choose from range A - E")

You can call chose.lower without the if statement without any consequences as far as I know. I don’t have any experience with using something like while choose ==“a”, bit it looks to me like if choose ==“a” would work just the same way, and be more readable.