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Easier than you think

Logic Level 2

When you list the integers from 1 to 100, how many 7's have you written down?

21 20 18 19

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Excel in math and science

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It's hard to learn from lectures and videos

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Used and loved by over 6 million people

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including olympiad champions, researchers, and professionals.

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by Siddharth Bhatnagar

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