Solve for Triangle: Finding the Missing Value in 33 + △ = 40

To solve the equation $33 + \triangle = 40$, we will follow these steps:

• Step 1: Write down the equation: $33 + \triangle = 40$.
• Step 2: Subtract 33 from both sides to isolate $\triangle$:
• $\triangle = 40 - 33$.
• Step 3: Perform the subtraction: $40 - 33 = 7$.

Therefore, the numerical value of the triangle $\triangle$ is $7$.

Accordingly, the correct answer choice is $7$, which matches choice 4.