The Missing Square Puzzle

If you rearragne the four shapes in triangle A and place them in triangle B, you will notice an additional square in triangle B.

How did this happen?

Magic Triangle Puzzle

Place the integers from 1 to 9 in one of the circles in the figure so that the sum of the integers along each side of the figure is 17. Determine the sum of the three integers placed in the corners. Can you try to solve it for other sums from 18 to 23?.

And a printable version of the magic triangle is here:

Counterfeit Coins Puzzle

There are 10 bags with coins. Each bag contains 2000 coins. Nine of them contain real coins weighing 10g each, and one contains counterfeit coins weighing 9g each. By one weighing on a digital scale find the bag with counterfeit coins?

And how would you solve it if 5 bags contained counterfeit coins?

Farmer, Goat, Wolf and Cabbage Puzzle

A farmer wants to cross a river and take with him a wolf, a goat, and a cabbage. There is a boat that can fit himself plus either the wolf, the goat, or the cabbage. If the wolf and the goat are alone on one shore, the wolf will eat the goat. If the goat and the cabbage are alone on the shore, the goat will eat the cabbage. How can the farmer bring the wolf, the goat, and the cabbage across the river?

8 Numbers Grid Puzzle

You are provided with a grid (as shown in the picture). Can you fill the squares with numbers 1-8 in a manner that none of the two consecutive numbers are placed next to each other in any direction (vertically, horizontally or diagonally?)