A list of numbers or diagrams that are in a particular order ... Look at the difference between one pattern and the next in the sequence. Here, 1 yellow circle and 2 red squares are being added ...

One poster @NguyenDung14133 trying to solve the riddle said: "D) 18". another user, @22Willem1, reckoned the answer was 18. Using the differences in the number pattern, you can use you problem ...

Lots of number patterns are possible. Author provided. Calculators have great potential in concept development. For example, what happens when you multiply or divide a number by 10 or 100?