Question

Hi I am new to python and I am practicing by making a simple calculator.
The program lets me input numerical values for meal, tax, and tip but when doing the calculation I get this error:

Traceback (most recent call last):
  File "C:/Users/chacha04231991/Desktop/pytuts/mealcost.py", line 5, in <module>
    meal = meal + meal * tax
TypeError: can't multiply sequence by non-int of type 'str'

The is the code:

meal = raw_input('Enter meal cost: ')
tax = raw_input('Enter tax price in decimal #: ')
tip = raw_input('Enter tip amount in decimal #: ')

meal = meal + meal * tax
meal = meal + meal * tip

total = meal
print 'your meal total is ', total

Answer 1

You need to convert your inputs from strings to numbers, e.g. integers:

meal = int(raw_input('Enter meal cost: '))
tax = int(raw_input('Enter tax price in decimal #: '))
tip = int(raw_input('Enter tip amount in decimal #: '))

You could also use the decimal type if you need to enter fractional monetary amounts.

from decimal import Decimal 
meal = Decimal(raw_input('Enter meal cost: '))
tax = Decimal(raw_input('Enter tax price in decimal #: '))
tip = Decimal(raw_input('Enter tip amount in decimal #: '))

I would advise you not to use floats for this because it will give rounding errors.