Problem 4 · 2024 Math Kangaroo
Easy
Geometry & Measurement
careful-countingarea
Bruno builds a big triangle out of small triangles that are all the same size. Some are already placed (shown grey). How many more small triangles does he need so that the big triangle is completely filled?
Show answer
Answer: B — 6
Show hints
Hint 1 of 3
The grey little triangles are already glued in; the white spaces are the holes still to fill.
Still stuck? Show hint 2 →
Hint 2 of 3
We only need to count the white triangles, because each hole needs exactly one more small triangle.
Still stuck? Show hint 3 →
Hint 3 of 3
Carefully point to and count every white triangle, one by one.
Show solution
Approach: count the white holes
- The grey triangles are already placed, so we just need to fill the white holes.
- Touch and count each white triangle one at a time.
- There are 6 white triangles, so Bruno needs 6 more.
Mark:
· log in to save