a,b and c are single digit natural numbers. If
Find
.
Details and Assumption is a three digit number of the form
This problem is a part of my set The Best of Me
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a a a a a a c a n b e w r i t t e n a s a ( 1 1 1 1 1 1 ) . Factoring 111111 gives us
1 1 1 1 1 1 = 3 × 7 × 1 1 × 1 3 × 3 7 ⇒ b × c × b c × ( 2 c − b ) × ( 2 b + c ) h a s t h e f a c t o r s 3 , 7 , 1 1 , 1 3 , 3 7 ⇒ b × c × ( 1 0 b + c ) × ( 2 c − b ) × ( 2 b + c ) h a s t h e f a c t o r s 3 , 7 , 1 1 , 1 3 , 3 7
Since b and c are single digit numbers, only 10b+c is a multiple of 37
⇒ 1 0 b + c = 7 4 o r 3 7 I f 7 4 , t h e n , b = 7 , c = 4 ⇒ b × c × ( 1 0 b + c ) × ( 2 c − b ) × ( 2 b + c ) = 7 × 4 × 7 4 × 1 × 1 8
But nor 11 neither 13 are its factors. I f 3 7 , t h e n , b = 3 , c = 7 ⇒ b × c × ( 1 0 b + c ) × ( 2 c − b ) × ( 2 b + c ) = 3 × 7 × 3 7 × 1 1 × 1 3 = 1 1 1 1 1 1 Hence a=1, b=3, c=7. ⇒ a b c = 2 1