Question

I am working on a program that needs to do the following:

Write a script that asks a user for a number. The script adds 3 to that number. Then multiplies the result by 2, subtracts 4, subtracts twice the original number, adds 3, then prints the result.

Here is my first solution:

#Prompt user for number
 number = input("Input a number")

#Print out the solution
 print number + 3 * 2 - 4 - (number * 2) + 3

And here is my second solution:

#Prompt user for number
 number = input("Input a number ")

#Add 3 to number
 print "Let's add 3"
 number1 = number + 3
 print number1

#Multiply by 2
 print "Let's multiply by 2"
 number1 = number1 * 2
 print number1

#Subtract 4
 print "Let's subtract 4"
 number1 = number1 - 4
 print number1

#Subtract twice the original number
 print "Let's subtract the original number twice!"
 number2 = number + number
 number1 = number1 - number2
 print number1

#Add 3
 print "...And finally, we add 3"
 number1 = number1 + 3
 print "Our sum is", number1

Which solution is correct, or are they both incorrect?

I know this is very basic, but I am learning to Program. I thought I would try out 2 different ways of writing this code.

Answer 1

Just add a pair of parentheses to your first version to correct it:

print (number + 3) * 2 - 4 - (number * 2) + 3

Otherwise, 3 * 2 would be evaluated with higher precedence than the additions and subtractions.

Note that the output does not depend on the number at all. Simplifying the expression shows that

print 5

does the same as the code above.