# Blog

## Counting threes

By David Shaw, 9 January 2019

Tilly started writing down numbers as she counted them out, “1, 2, 3, 4 …” She was interrupted when she was writing down the 33rd 3. What number was she in the middle of writing?

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## This code’s for oldies

By David Shaw, 12 December 2018

If you’re sitting there twiddling your thumbs, see if you can decode this message. If you need a hint, you can always phone a friend! 3666882255533 443355544499 339987772

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## Number cruncher

By David Shaw, 28 November 2018

I have four different whole numbers written on a piece of paper. The largest number is four bigger than the smallest. The middle two numbers are even. If I add all four numbers together, I get 12. What are my numbers?

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## Half past angle

By David Shaw, 14 November 2018

At half-past three, what is the angle between the hands of a clock?

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## A fish tank on the table

By David Shaw, 31 October 2018

Jenny had a short, wide fish tank. She wanted to change the water, so she put the fish tank on a table and put a tall bucket on the floor right underneath. She was about to get a hose and siphon the water into the bucket, but before she started, she did some measuring.

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## Tom’s quilt brainteaser

By David Shaw, 17 October 2018

Tom’s just finished sewing a quilt! It’s made of lots of equal-sized squares of fabric sewn together. Currently, it’s 12 squares long and six squares wide. Tom tried putting the quilt on his bed, but it’s the wrong shape.

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## Making change

By David Shaw, 3 October 2018

Australia has six coins that are commonly used – 5 cents, 10 cents, 20 cents, 50 cents, $1 and $2. How many different ways can you make exactly 50 cents in Australian coins?

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## Planning to party

By David Shaw, 19 September 2018

On Sunday, 1 January, Latda announced her New Year’s resolution. “Throughout this year, on the fifth Sunday of the month, I’ll throw a party!” How many fifth Sunday parties did Latda celebrate that year?

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## Peter’s staircase

By David Shaw, 5 September 2018

Peter’s just finished building a new staircase up to the attic. It just fits along the four-metre-long wall of his lounge room, and it’s three metres tall. It has exactly 15 steps. Peter wants to have a carpet running along the staircase. How long does it need to be?

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