Calculation using class

[Idk507]

class cal():
def init(self,a,b):
self.a=a
self.b=b
def add(self):
return self.a+self.b
def mul(self):
return self.a*self.b
def div(self):
return self.a/self.b
def sub(self):
return self.a-self.b
a=int(input("Enter first number: "))
b=int(input("Enter second number: "))
obj=cal(a,b)
ch=1
while ch!=0:
print("1. Add")
print("2. Subtraction")
print("3. Multiplication")
print("4. Division")
ch=int(input("Enter choice: "))
if ch==1:
print("Result: ",obj.add())
elif ch==2:
print("Result: ",obj.sub())
elif ch==3:
print("Result: ",obj.mul())
elif ch==4:
print("Result: ",round(obj.div(),2))
elif ch==0:
print("Exiting!")
else:
print("Invalid choice!!")

print()