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AMO 2027 Grades 9-11 SET 5 - Self-study Question 2

AMO · AMO 2027 Grades 9-11 SET 5 - Self-study

Question 2

How many four-digit whole numbers contain the adjacent digit pair “22”, with no intervening digit? For example, 4322 qualifies, but 4232 does not.

Enter one positive integer, without units.