BrainTwister #24: Coin flips

#24 Coin flips

set by James Grime

We can flip this triangle made of coins, from one pointing upwards to one pointing downwards, by moving three of the coins (coloured dark blue), as shown in the image below.

However, it is also possible to flip this triangle upside down by moving two coins. Can you find a way?

What about a triangle with four rows? What is the fewest number of coin moves needed to flip that triangle upside down?

How about bigger triangles? Is there a general rule?

Solution next week

#23 Four points, two distances

Solution

There are…