MathDB
Two identical digits

Source: UMD 2023 I #16

October 23, 2023
UMDalgebra

Problem Statement

How many integers between 123123 and 789789 have at least two identical digits, when written in base 10?10? a. 180b. 184c. 186d. 189e. 191 \mathrm a. ~ 180\qquad \mathrm b.~184\qquad \mathrm c. ~186 \qquad \mathrm d. ~189 \qquad \mathrm e. ~191
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