Define the following numbers as
A = ( 1 6 8 1 + 1 7 5 1 + 6 0 0 1 ) ( 1 6 8 1 + 1 7 5 1 − 6 0 0 1 ) ( 1 6 8 1 + 6 0 0 1 − 1 7 5 1 ) ( 1 7 5 1 + 6 0 0 1 − 1 6 8 1 )
B = ( 2 4 0 1 + 2 6 0 1 + 6 2 4 1 ) ( 2 4 0 1 + 2 6 0 1 − 6 2 4 1 ) ( 2 4 0 1 + 6 2 4 1 − 2 6 0 1 ) ( 2 6 0 1 + 6 2 4 1 − 2 4 0 1 )
C = ( 4 3 2 1 + 5 4 0 1 + 7 2 0 1 ) ( 4 3 2 1 + 5 4 0 1 − 7 2 0 1 ) ( 4 3 2 1 + 7 2 0 1 − 5 4 0 1 ) ( 5 4 0 1 + 7 2 0 1 − 4 3 2 1 )
Evaluate the digit sum of A 1 + B 1 + C 1 .
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I think all you forgot to multiply by 16 as A turned out to be S A 2 (and the same for B and C) meaning that the final answer was 4 times of the actual. However the answer still remained :)
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As planned, it all cuts out (lovely ratios).
I got A = 2 7 5 6 2 5 0 0 0 0 1 , B = 6 5 8 0 4 5 4 4 0 0 1 , C = 3 7 7 9 1 3 6 0 0 0 0 1
which is equivalent to A = 5 2 5 0 0 2 1 , B = 8 1 1 2 0 2 1 , C = 1 9 4 4 0 0 2 1
and 5 2 5 0 0 + 8 1 1 2 0 + 1 9 4 4 0 0 = 3 2 8 0 2 0
the final answer to enter 3 + 2 + 8 + 0 + 2 + 0 = 1 5
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By Heron's Formula, we have that the area S of the triangle with sides a , b , c can be represented by 1 6 S 2 = ( a + b + c ) ( a + b − c ) ( a + c − b ) ( b + c − a ) .
For the first numbers, see that ( 1 6 8 1 ; 1 7 5 1 ; 6 0 0 1 ) = ( 7 ⋅ 2 4 ⋅ 2 5 2 5 ; 7 ⋅ 2 4 ⋅ 2 5 2 4 ; 7 ⋅ 2 4 ⋅ 2 5 7 ) .
Because 7 2 + 2 4 2 = 2 5 2 , we have that S A = 2 ⋅ ( 7 ⋅ 2 4 ⋅ 2 5 ) 2 7 ⋅ 2 4 ⇔ A = 1 6 ( 2 ⋅ ( 7 ⋅ 2 4 ⋅ 2 5 ) 2 7 ⋅ 2 4 ) 2 = 2 1 0 0 0 0 2 1 .
Similarly, for the second number we have 2 4 0 = 1 0 ⋅ 2 4 , 2 6 0 = 1 0 ⋅ 2 6 , 6 2 4 = 2 4 ⋅ 2 6 and B = 3 2 4 4 8 0 2 1 . For the third number, check 4 3 2 = 1 8 ⋅ 2 4 , 5 4 0 = 1 8 ⋅ 3 0 , 7 2 0 = 2 4 ⋅ 3 0 and C = 7 7 7 6 0 0 2 1 .
Finally, A 1 = 2 1 0 0 0 0 , B 1 = 3 2 4 4 8 0 , C 1 = 7 7 7 6 0 0 , so 2 1 0 0 0 0 + 3 2 4 4 8 0 + 7 7 7 6 0 0 = 1 3 1 2 0 8 0 . and our desired answer is 1 + 3 + 1 + 2 + 8 = 1 5 .