2.3 1.1

Part of 2022 CMIMC

Problems(1)

2022 Alg/NT Div 1 P1 (Div 2 P3)

Source:

How many 4-digit numbers have exactly

9

divisors from the set

\{1,2,3,4,5,6,7,8,9,10\}

?
Proposed by Ethan Gu

algebranumber theory