# Blog

## Brainteaser: Skipping stairs

By Ariel Marcy, 21 March 2024

Flora likes to run up stairs as fast as she can! Sometimes she lands on every stair and sometimes she skips a stair, taking two in one stride. This gets her thinking: how many different ways can she run up a staircase?

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## Secret pairs

By Ariel Marcy, 12 March 2024

Lavonne is testing a secret code with her friend Jack. First, she picks 3 different secret numbers between 1 and 9. Then she finds the sum of each pair of numbers. Lavonne wants to know if Jack can figure out the original secret numbers just from the sums?

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## Artful measuring

By Ariel Marcy, 10 January 2024

Holly loves drawing and her favourite colours have been sharpened a lot. Her most favourite colour, rose, is exactly 3cm long. She discovers that the teal pencil is exactly 4cm, and the almond pencil is exactly 6cm. What lengths from 1-10 cm can Holly make with her pencils?

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## 2023’s Best Brainteasers

By Ariel Marcy, 14 December 2023

In 2023, Double Helix readers busted a bunch of brainteasers! Here are the tippy-top, most popular puzzles of the year.

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## Same, same, same but different

By Ariel Marcy, 6 December 2023

Can you find a different set of 5 positive whole numbers with the same stats?

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## Great Barrier Reef A Quick Quiz

By Ariel Marcy, 21 November 2023

The Great Barrier Reef is one of Earth’s 7 natural wonders. We’re wondering if you’ll be a natural at this quiz! Wade into the Reef’s fantastic ecology and aim for a dive out of five.

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## Magical weights

By Ariel Marcy, 14 November 2023

Difficulty: Fun Ellen has a set of 6 weights that come in pairs. One pair is a magical set of negative weights (think helium balloons that take weight away). 2 of the weights are 1 kilogram each, 2 of the weights are 5 kilograms each, and the 2 magical weights are -3 kilograms each. Ellen […]

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## Nifty triangle numbers

By Ariel Marcy, 6 November 2023

Difficulty: Fun Triangular numbers are numbers that can be formed into a triangle. For example, 3 is a triangular number with 2 dots on the bottom row and 1 dot on top row forming an equilateral triangle of 3 dots. 6 is the next triangular number with 3 dots on the bottom, 2 dots in […]

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## Friendship circles

By Ariel Marcy, 23 October 2023

Difficulty: Tricky Anas is making a map of his friend group. In his map, each circle is a person. A line joins 2 circles if and only if those 2 people are friends. Using the clues below, can you figure out who goes where on the map? 1. Anas has 3 friends: Ruth, Mitra, and […]

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## Crack the computer clock

By Ariel Marcy, 4 October 2023

Difficulty: Tricky Ahmad’s computer scientist mother gives him a binary stopwatch that counts minutes using only 1’s and 0’s – just like a computer! The binary stopwatch has 6 placeholders where the 1’s and 0’s appear. When the binary stopwatch is reset, all the placeholders are zeros. Ahmad finds a regular stopwatch, resets both stopwatches, […]

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