We invite you to solve the English version of the RTSdécouverte monthly problem:
House of Cards
To construct a house of cards, take two cards and put them together in a triangle. You have built a one-storey house.
To build a second floor, add a pair of cards next to the first pair. Then, place a card horizontally and place a third pair of cards on top of it.
Continuing like this, you can (in theory) build a house of cards with as many storeys as you wish.
How many cards do you need to build 100-storey house?