Choose the correct product notation or summation for the expression. I need to choose weather this is a product notation or a summation. I can figure out which one it is.
I have this expression:
$$2 \times 4 \times 6 \times 8 \times 10 \ldots \times 40$$
The answer is either:

$$\sum_{m=2}^{40} m$$

or 

$$\prod_{m=2}^{40} m$$


Neither of your proposal is correct.
For your first guess, it means $$2+3+4+\ldots+ 40$$
For your second guess, it means $$2(3)(4) \ldots (40)$$
You are multiplying even numbers, it should be
$$\prod_{i=1}^{20} (2i)$$
