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How many 1s does it take to write out the number eleven thousand, eleven hundred and eleven?

A farmer goes to the local mill to get some wheat ground into flour. The miller doesn’t ask for money – instead, they take one tenth of the wheat as payment. If the farmer wants 100 kilograms (kg) of flour at the end, how much wheat should they bring?

The soma cube is a tricky puzzle! First, you’ll glue some cubes together into strange shapes. Then see if you can get those shapes to come together!

Difficulty: Extreme! Srinivasa lives in a house on a short street, with houses on one side. The houses are numbered 1, 2, 3 and so on. He was practicing his addition when he noticed something strange.

Difficulty: Tricky Mabel wanted to play noughts (O) and crosses (X), but she didn’t have anyone to play with. So she just took one go after another. Somehow, Mabel put Xs in 6 of the 9 squares without making a line of 3 Xs. Can you draw the board and work out which squares have…

Difficulty: Tricky Willow has a staircase with 7 steps. She likes to walk down the staircase in different ways. Sometimes she takes 1 step at a time, and other times she skips a step and goes 2 at a time. If Willow mixes up these 2 types of steps, how many different ways can she…

Difficulty: Extreme! These 2 brothers sold oranges for a living. On Monday: Josh priced his oranges at 2 for $3. He sold 30 oranges for $45. Zach priced his oranges at 3 for $4. He sold 30 oranges for $40. On Tuesday, they combined their prices, and sold their oranges in groups of (2 +…

Difficulty: Tricky Jasper had a regular (sides and angles all the same) hexagon with 10-centimetre sides, and 3 regular triangles with 10-centimetre sides. He put the side of a triangle against every second side of the hexagon. How many sides did this final shape have?

Difficulty: Tricky Keira is getting ready for school: She has 3 different shirts – one black, one white and one red. She has 3 different pairs of pants – one black, one white and one red. She has 3 different pairs of shoes – one black, one white and one red.

Difficulty: Tricky Last week I flew from Canberra to Brisbane. The plane took off at 2.00 pm, flew 1,800 kilometres at 900 kilometres per hour, and landed at 3.00pm. On the way home from Brisbane, the plane took off at 8.00 pm. Assuming it flew at the same speed, when did it land in Canberra?