# Coin Puzzle – Triangular Number

I often introduce new puzzles to my kids. I believe puzzles have many important benefits for them. It develops their problem solving skills, and persistence. And it also boost their confidence as they solve it. Today, we tried solving some coin puzzle. Do you know that numbers can also have shapes. For example, the number 10 is a triangular number because you can arrange any ten similar items into the shape of an equilateral triangle. When you do this, the triangle would have four of these items on each side. Can you figure out more triangular numbers ? How about 3,6, 16 ?

For this puzzle, place 10 pennies on a flat surface in the shape of a triangle. Just by moving three pennies, turn it into a triangle that points in the opposite direction.

#### Still wondering how to solve it ?

Move the rightmost penny in the fourth row to the rightmost column of the second row.

The leftmost penny in the fourth row moves to the leftmost column of the second row.

The one penny in the top row moves to the row in front of the two pennies left in the fourth row.

Voila , your triangle is now facing in the opposite direction. Here are some good puzzle books to have in your book shelves.

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The puzzles in the book 125 Best Brain Teasers of all time cover 5 levels of difficulty and there are a variety of wordplay, math, and logic brainteasers. Some of the problems have related short historical facts. I found that few of the brain teasers are redundant. And , for some questions there can be multiple solutions but only one solution is given. It gives you a chance to work your brain and find them out yourself.

There are 78 riddles in the book Of Course ! The Greatest Collection of Riddles & Brain Teasers For Expanding Your Mind and I love how each riddle is unique and engaging which keeps the content fresh. The riddles are easy to read and understand. The questions are crafted in such a way that they prompt you to think and there comes a moment of clarity where you say “of course!” . Overall, it is a fun book your kids would enjoy.

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While you are here, check out some more puzzles also