#a)
print('Input n: ')
n = input()
if int(n) < 0:
print('Incorrect input')
else:
sum = 0
for i in range(int(n) + 1):
sum += i
print('Sum is ', sum)
##
#b)
print('Input n: ')
n = input()
if int(n) < 0:
print('Incorrect input')
else:
sum = 0
for i in range(int(n) + 1):
sum += i*i
print('Sum is ', sum)
##
#c)
print('Input n: ')
n = input()
if int(n) < 0:
print('Incorrect input')
else:
sum = 0
for i in range(0, int(n) + 1, 2):
sum += i
print('Sum is ', sum)
##
#d)
sum = 0
for i in range(10, 100, 1):
sum += i
print('Sum is ', sum)
цифры на компьютере.67845312