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How many 3-digit numbers contain exactly one 1 and one 2?

 Oct 15, 2021
 #1
avatar+115340 
+1

you want      

12*    in any order where * can be 0,3,4,5,6,7,8,9  

 8*3! = 8*6=48

except it cannot start with 0 so it cant be  012 or 021

 

48-2 = 46 possibilities

 Oct 15, 2021

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