1. **State the problem:** Two number cubes (dice) each numbered 1 through 6 are rolled 300 times. We want to find how many times the sum of the two dice is exactly 7. 2. **Formula and rules:** The total number of outcomes when rolling two dice is $6 \times 6 = 36$ because each die has 6 sides. 3. **Count favorable outcomes:** The pairs that sum to 7 are: $(1,6), (2,5), (3,4), (4,3), (5,2), (6,1)$, which is 6 outcomes. 4. **Calculate probability:** The probability of the sum being 7 is $$\frac{6}{36} = \frac{\cancel{6}}{\cancel{36}} = \frac{1}{6}.$$ 5. **Expected number of times in 300 rolls:** Multiply the probability by the number of trials: $$300 \times \frac{1}{6} = 50.$$ **Final answer:** You would expect the sum to be exactly 7 about 50 times in 300 rolls.