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Sienna’s teacher is writing up a wicked problem. First, the teacher writes all the numbers from 1 to 99 and then erases 10, 20, and all the other numbers that end in 0. “Listen up! Multiply all these numbers. Tell me the last digit and I’ll give you full marks on your next assignment.”

This quiz is for all you maths wizards. Can you maximise your score, or does this quiz have your number?

Difficulty: Fun Sienna’s teacher is writing up a wicked problem on the board. First, the teacher writes all the numbers from 1 to 99. Then they erase 10, 20, and all the other numbers that end in 0. “Listen up!” the teacher announces. “I want you to multiply all the numbers on the board.

Which two whole numbers – without any zeros – multiply together to make 1 000 000?

How did people multiply before calculators were invented? You could try doing it in your head, but you could also use a mechanical calculator, such as this set of Napier’s bones.