In the given expression:

$14 \div 2 \square 3 - 6 = 15$

The box (square) represents a missing mathematical operation. Let's determine what operation belongs in the square so that the equation is correct.

First, let's break down the current operations we know:

1. $14 \div 2 = 7$
2. Then we apply the missing operation between $7$ and $3$, and then subtract 6, to obtain 15.

Try each basic operation (addition, subtraction, multiplication, division):

• If the operation is multiplication: $7 \times 3 = 21 \quad \text{and} \quad 21 - 6 = 15$ This is correct.

Thus, the missing operation is multiplication ($\times$).

The correct equation is:

$14 \div 2 \times 3 - 6 = 15$

Would you like further clarification or more details?

Here are five related questions to consider:

1. What is the importance of the order of operations (PEMDAS)?
2. How would the equation change if the box represented division instead?
3. Can you solve similar equations with different unknown operations?
4. How would parentheses affect the solution?
5. Can the result be different if the operations are performed in another order?

Tip: Always remember to follow the correct order of operations (PEMDAS: Parentheses, Exponents, Multiplication/Division, Addition/Subtraction) to avoid mistakes in solving mathematical expressions.