Python for loops for repeated addition

Question

I am trying to create a program that creates a multiplication table of n x n. It's required for the assignment to use repeated addition instead of the multiplication function.

This is the code I have so far:

def main():
import math
print('Hello!')
n = (abs(eval(input("Enter n for the multiplication table n x n: "))))
n = int(n)
a = 0
for i in range(1,n+1):
    for x in range(1,n+1):
        a = i+a
        print(i,' * ',x,' = ',a)
main()

It gives me an output like this:

Hello!
Enter n for the multiplication table n x n: 4
1  *  1  =  1
1  *  2  =  2
1  *  3  =  3
1  *  4  =  4
2  *  1  =  6
2  *  2  =  8
2  *  3  =  10
2  *  4  =  12
3  *  1  =  15
3  *  2  =  18
3  *  3  =  21
3  *  4  =  24
4  *  1  =  28
4  *  2  =  32
4  *  3  =  36
4  *  4  =  40

The output is obviously incorrect, so what can I change/add to fix the calculations?

Please please please, do not use eval(input(...)). Use int(input() in this case. — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Mar 5, 2017 at 20:37

Lavaman65 · Accepted Answer · 2017-03-05 20:38:18Z

5

You have a variable a inside of your nested for loops that you continuously add values to for different values of the multiplication table. Instead of adding i to a each iteration, let a = i*x. This will give you the correct value of multiplication each time. However, if you really want to do it with repeated addition, set a = 0 outside of the second for loop, but inside the first, like so:

for i in range(1,n+1):
    for x in range(1,n+1):
        a = i+a
        print(i,' * ',x,' = ',a)
    a = 0

answered Mar 5, 2017 at 20:38

Lavaman65

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2 Comments

juanpa.arrivillaga Over a year ago

I would suggest to use .format in this case, it makes things cleaner: print("{}*{} = {}".format(i, x, acc))

Rebekah Lynn Wildes Over a year ago

That was what I was missing. Thank you so much!

mmghu · Accepted Answer · 2017-03-05 20:36:31Z

0

For the print statement try using instead:

print(i,' * ',x,' = ',i*x)

I'm not certain what you are using the 'a' variable for, but if you'd like to output the multiplication of i and x still using a, instead keep your code the same and just change what you have for a in your nest for loop:

a = i*x

Hope this helps!

answered Mar 5, 2017 at 20:36

mmghu

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2 Comments

Rebekah Lynn Wildes Over a year ago

That worked, but for the assignment, I can't use the multiplication function, i have to use repeated addition.

mmghu Over a year ago

Ah, if that's the case I'd follow UnknowableIneffible's solution, as he addressed how to solve the problem with repeated addition.

user5710871 · Accepted Answer · 2017-03-05 20:41:04Z

0

In your for loop, you're always incrementing the variable 'a' by itself added to 'i' each time, instead you should multiply i*x

print("Hello!")

n = input("Enter n for the multiplication table n x n: ")
n = int(n)

result = 0

for i in range(1,n+1):
    for j in range(1, n+1):
        result = i*j
        print(i," * ", j, " = ", result)

answered Mar 5, 2017 at 20:41

user5710871

1 Comment

juanpa.arrivillaga Over a year ago

Why do you have result = 0? It is no longer necessary.

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