# Blog

## Sleepy time brainteaser

By Chenxin Tu, 10 May 2023

Lisa had a difficult time falling asleep on Wednesday night, so she began counting sheep. How many sheep did she count?

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## Circle gaps brainteaser

By Ariel Marcy, 26 April 2023

What is the area of the orange star in the centre? The blue circles each have an area of 3 square centimetres, and the big square has sides that are 4 centimetres long.

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## Trench diving brainteaser

By Ariel Marcy, 12 April 2023

Jing is taking her submarine to the bottom of an ocean trench. The first day she goes half the distance to the bottom of the trench.

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## Tricky triangle brainteaser

By Ariel Marcy, 29 March 2023

Time for a tricky triangle teaser! If the purple shaded triangle has an area of 2, what is the area of the largest triangle?

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## Prime number brainteaser

By David Shaw, 9 March 2023

Difficulty: Extreme 123,456,789 is not a prime number. Is it possible to reorder its digits to give a prime number?

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## George’s lollies brainteaser

By David Shaw, 23 February 2023

Difficulty: Extreme! George bought a bag of 70 lollies on Monday. He didn’t eat many on Monday, but he really liked the flavour. Every day after that he ate three more lollies than he had the previous day. The next Monday, George was about to eat his first lolly for the day and noticed the […]

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## As easy as pi – a quick quiz

By Fiona Midson, 22 February 2023

It’s time to be irrational and celebrate π (Pi) Day! Will you slice up this quiz and get 5/5 or are you going to eat humble pie?

## Australian coins brainteaser

By David Shaw, 15 February 2023

Difficulty: Fun Jane has some Australian silver coins in her pocket. When buying an apple, she realises she has more than $1 in silver coins, but can’t make exactly $1 with her coins. How is this possible? (Silver Australian coins come in 5c, 10c, 20c, and 50c.)

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## Pool leak brainteaser

By Elizabeth Thomsen, 5 January 2023

Difficulty: Fun While Eddie is away on holidays his swimming pool has a leak. Each day it loses half the water still in the pool. Normally, it’s 1.6 metres deep, but when Eddie gets home there is only 10 centimetres of water in the bottom. How long has the pool been leaking?

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