check if a number is triangular

Question

Hello I am trying to figure out of a number is triangular so I started writing my logical train of thought and ran into a little problem with my code I get an error that states "TypeError: 'int' object is not callable" any help is most appreciated. here is what my code looks like that is causing this issue:

x = int(input("Please enter an int: "))
i = x(x+1)/2
l = []
l.append(i)
print(i)

Welcome to Stack Overflow. In your own words, where the code says `x(x+1)/2`, what do you expect this to mean? Why? — Karl Knechtel, Sep 16 '22 at 16:22
@KarlKnechtel was trying to multiply x by x+1 / 2. i believe John and Ben have solved my dilemma, thank you for the warm welcome. — serge, Sep 16 '22 at 16:24
@serge By the way, `y` is a triangular number if and only if `1 + 8*y` is a perfect square. — Ben Grossmann, Sep 16 '22 at 16:25

score 1 · Answer 1 · answered Sep 16 '22 at 16:22

1

You have to use the * operator for multiplication.

x = int(input("Please enter an int: "))
i = x*(x+1)/2 # << fixed here
l = []
l.append(i)
print(i)

answered Sep 16 '22 at 16:22

blackbrandt

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check if a number is triangular

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