What is 48÷2(9+3)?
I was having a heated debate with my colleague and we can't agree on the answer to this question: Does 6÷2(2+1) equal 9 or does it equal 1?
Depends on whether $6 \div 2 \times (2+1)$ means $(6 \div 2) \times (2+1)$ or $6 \div (2 \times (2+1))$. The former yields $9$, the latter $1$. In a programming language like Haskell, the ambiguity would be resolved by specifying what the priority of each operator is, and whether such operator is left- or right-associative.
Remark: Note that in this context, an operator is a binary arithmetic operation. Thus, addition, subtraction, multiplication, and division are operators.