Look carefully at each line of numbers in the number
pyramid. What number should replace the question
mark in the middle of the bottom line? Explain why.
8 2 5 2 1 2 4 2 1 1 2 1 3 1 2 1 1 2 1 1 ? 1 1 2 1
The number 2 should replace the question mark. Each
horizontal row adds up to one more than the one
above it, so the last row must add up to 12.