# Blog

## 4 equal rectangles

By Ariel Marcy, 13 September 2023

Difficulty: Fun The big rectangle below is made from 4 small rectangles. All the small rectangles are equal, meaning that they have the same size and shape. If the small rectangle’s short side is 8 centimetres, what is the length (long side) of the bigger rectangle?

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## An odd observation

By Ariel Marcy, 30 August 2023

Difficulty: Tricky Alex is playing a dice game with 2 standard 6-sided dice, one red and one blue. Each die has faces numbered from 1 to 6. Alex rolls both dice and adds up the numbers on the top faces. After a while, Alex notices that the sums are always between 2 and 12 and […]

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## Divide by this

By Ariel Marcy, 10 August 2023

Difficulty: Extreme A teacher wrote a whole number on the whiteboard and asked her students to say what numbers it could divide by. The 1st student said, “the number is divisible by 1.” The 2nd student said, “the number is divisible by 2.” The 3rd student said, “the number is divisible by 3.” And this […]

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## A cup conundrum

By Ariel Marcy, 26 July 2023

Difficulty: Tricky Fernando has 3 water-tight containers that measure 3 cups, 9 cups, and 20 cups (for brevity, these are referred to as C3, C9, and C20, respectively). The containers have no markings to indicate other volumes, so there’s no way to know when a container is, say, half full. The containers have nice spouts, […]

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## Welcome to the dog show

By Ariel Marcy, 13 July 2023

Difficulty: Fun There are 50 total dogs signed up for a dog show. There are 30 more small dogs than large dogs. How many small dogs have signed up to compete in the show?

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## Out Of This World

By Ariel Marcy, 29 June 2023

Difficulty: Fun Mariana the astronaut weighs 51 kilograms on Earth and 8.5 kilograms on the Moon. Mariana is training Javier to go to the Moon. If he weighs 78 kilograms on Earth, how much will he weigh on the Moon?

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## Great to Meet You! brainteaser

By Ariel Marcy, 22 June 2023

Difficulty: Tricky You’ve just joined a new Scouts group! You meet 4 other new people, and everyone is going around giving handshakes. If everyone shakes hands with everyone else exactly once, how many handshakes will there be in total? (Remember you can’t shake hands with yourself.)

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## Regeneration brainteaser

By David Shaw, 8 June 2023

A sea sponge gets attacked by a shark and is ripped into 100 pieces. Luckily, sea sponges can join back together after they’ve been broken apart. Some pieces form into groups of 7, and the rest form into groups of 29. In the end, there are no pieces left. How many sponges do we end […]

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## Sequence This

By Ariel Marcy, 24 May 2023

Difficulty: Tricky Consider the following sequence of numbers. What number comes next? 1, 1, 2, 3, 5, 8, 13…

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