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How many five-digit numbers have distinct digits which are decreasing from left to right? (For example, 96531 is such a number.)

 May 1, 2021
 #1
avatar+84 
+1

Say the number is ABCDE

 

"A" would have 9 solutions 1-9

"B" would also have 9 solutions 1-9 - one number +zero

"C" would have 8 solutions

"D" would have 7 solutions

"E" would have 6 soultions

9*9*8*7*6 is 

27216

 

 

:)

 May 1, 2021
 #2
avatar+84 
0

its wrong srry

mathisopandcool  May 1, 2021

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