Natasha has many sticks of length 1. Each stick is coloured blue, red, yellow or green. She wants to make a 3 × 3 grid, as shown, so that each 1 × 1 square in the grid has four sides of different colours.
What is the smallest number of green sticks that she could use?
Sign in or create an account to reveal answers, view the solution, and save your progress. Create a free account to unlock practice and keep track of your work.
Grey Kangaroo 2019 (2019)
One puzzle per day. Cryptarithm, Magic Square, Summit. No sign-up required to play.
Play daily puzzle →Interactive problems and curated lessons—water pouring, magic squares, knight's tour, and more.
Browse library →See how you rank. Top solvers by problems solved correctly. Sign in to climb the ranks.
View leaderboard →Grey Kangaroo 2019 (2019)