Why is 15 + 15 different from 15 * 2?

Question

(Apologies if the tag is incorrect. I can't find a "Multiplication" tag or similar)

I'm going to be adding a set of 5 numbers up and dividing them to get the average for a java game I am making.

However, there seems to be something wrong with it. I would have thought 15 + 15 / 2 would have been 15, however that seems incorrect.

However, 15 * 2 / 2 yields the expected result.

What is the difference here? Will doing counting up the variables and dividing them by the amount of variables work correctly in my game?

Answer 1

You should probably write $(15+15)/2$ with parentheses and this will yield $15$.

Note that $22.5$ is $15+(15/2)$. In fact Google shows you that this is what it is calculating (taking into account the conventional order of operations).

Answer 2

Well when you write 15+15/2, the interpretation is $15+\dfrac{15}{2}$. You need brackets to solve this ambiguity: $\dfrac{(15+15)}{2}$

Answer 3

Order of Operations: Division comes before addition. So when you input 15+15/2 you get 15+7.5. To get the answer you want input (15+15)/2.