Problem 8 · 2022 Math Kangaroo
Medium
Spatial & Visual Reasoning
spatial-reasoning
The picture shows one object made up of 5 identical building blocks. How many building blocks touch exactly 3 others?
Show answer
Answer: B — 2
Show hints
Hint 1 of 2
Go block by block and count how many other blocks each one is pressed flat against (sharing a whole face).
Still stuck? Show hint 2 →
Hint 2 of 2
You are looking only for the blocks that touch exactly three others - not two, not four.
Show solution
Approach: count the touching neighbours of each block
- Pick each of the five blocks in turn and count how many other blocks share a flat face with it.
- The blocks at the ends touch only one or two others, but two of the middle blocks each touch three others.
- So exactly 2 blocks touch three others, and the answer is 2.
Mark:
· log in to save