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How many 9's are there between 1 and 100?

Twenty 9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99

Why this works

This riddle plays with the concept of counting occurrences of the digit '9' rather than the number itself. Between 1 and 100, you find '9' appearing in two forms: as a standalone number (9) and as part of other numbers (19, 29, etc.) in the tens place. Additionally, in the range from 90 to 99, '9' appears in both the tens and units places, adding up to a total of twenty instances. Hence, when you count all the occurrences of '9', you arrive at the answer: twenty!

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Common Wrong Answers

“10”

This guess only counts the 9s in the tens place (9, 19, 29, ...), but it ignores the 9s in the units place of the numbers 90 to 99.

“9”

This guess only counts the single occurrence of the digit '9' in the tens place (9), missing all occurrences in the units place and the other numbers.

“11”

This guess overestimates the count by mistakenly including only the '9's in 90 to 99 and miscounting other occurrences.

Numbers

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