Let the number be 100 a + 10b+c
none of a,b, c can be > 5 as 6! = 720 and 7! = 5040 > 1000
one of them that is b or c= 5 ( a cannot be 5 as 5! = 120 and 5! + 4! + 3! < 200)
so a = 1, b= 5, c = ? or a = 1, b = ? , c = 5 ( it has to be < 5)
if a = 1 , b = 5 we get 1 + 120 + c ! > 150 and < 160
39 >c! > 29 and so there is no c
if a = 1, c = 5 we get 1 + 120 + b! = 105 + 10 b
so b = 4 and the number is 145
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