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Rita is making lamingtons for her birthday party and cuts them precisely into 5-centimetre cubes. While playing around with an antique balance scale, she discovers that one lamington is equal to 50 grams plus half a lamington. At her party, she eats one and a half lamingtons. How much did Rita’s dessert weigh?

Double Helix Extra readers really got busy with brainteasers in 2024! Let’s do a count down of your top 5…

Here are eight 8s, 8 8 8 8 8 8 8 8. Put some plus signs in there to make 1000.

We’ve written a code using two different prime numbers less than 10. We then multiplied these two primes and used the resulting “code number” to shift the alphabet forward to new letters. Can you use the clues above to decode this message: DRO QYVN SC LEBSON SX DRO QKBNOX.

Right before the bell rings, Jeri’s teacher throws up a problem on the board: “I’m thinking of a number. When I add its digits together and multiply by seven, I get the number I first thought of. The number is under 40.” Can you help Jeri find the number before class is dismissed?

Can you solve this grid-based logic puzzle about NASA? You are doing a science project about four of NASA’s spacecraft: Clipper, DAVINCI, Dragonfly and MAVEN. Each spacecraft will visit another planet in the solar system: Venus, Mars, Jupiter and Saturn. They also have different launch dates: 2013, 2024, 2028 and 2030.

A team of geologists are using the latest technology to drill into the Earth’s ocean floor and look at the rock underneath! They manage to drill a total of 1250 metres (based on a recent true story!). But the drilling gets harder the deeper they get.

Eight people come together for a very important meeting. How many ways can just one person sit in the wrong chair?

In this puzzle, each Aussie animal stands for a number. Each animal represents the same number throughout the puzzle. Can you use the first three mathematical equations to figure out the answer to the last equation?

A team of engineers have invented a new, stretchy battery that is clear. Another team have invented a jelly-like battery that is rainbow coloured. Both teams want to compare how long their batteries last to a regular, silver AA battery.