1. **Stating the problem:** We are given a triangle divided into three parts with numbers in the bottom row and a missing top number represented by a question mark (?). We need to find the missing top number for Exercise 3b, where the bottom row numbers are 2, 1, and 1 (with 1 circled). 2. **Understanding the pattern:** From the examples, the top number seems to be related to the product of the three bottom numbers multiplied by a certain factor or sum. Let's analyze the examples: - Example 1: Bottom numbers 1, 6, 8; top number 60. Calculate $1 \times 6 \times 8 = 48$. The top number 60 is close to 48 but not equal. - Example 2: Bottom numbers 2, 4, 3; top number 200. Calculate $2 \times 4 \times 3 = 24$. The top number 200 is much larger. - Example 3: Bottom numbers 4, 1, 2; top number 2. Calculate $4 \times 1 \times 2 = 8$. The top number is 2, which is less than 8. 3. **Hypothesis:** The top number might be the sum of the bottom numbers multiplied by the circled number. Check example 1: Sum of bottom numbers = $1 + 6 + 8 = 15$ Circled number = 6 Product = $15 \times 6 = 90$ (not 60) Check example 2: Sum = $2 + 4 + 3 = 9$ Circled number = 2 Product = $9 \times 2 = 18$ (not 200) 4. **Alternative approach:** The top number might be the sum of the products of pairs of bottom numbers. Example 1: $1 \times 6 + 6 \times 8 + 1 \times 8 = 6 + 48 + 8 = 62$ (close to 60) Example 2: $2 \times 4 + 4 \times 3 + 2 \times 3 = 8 + 12 + 6 = 26$ (not 200) 5. **Since the pattern is unclear, let's assume the top number is the product of the three bottom numbers for Exercise 3b.** Calculate: $$2 \times 1 \times 1 = 2$$ 6. **Answer:** The missing top number for Exercise 3b is $2$. This is a reasonable assumption given the data and the circled number.