G R _ N D F _ T H _ R
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6 6
_ N D
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6 .
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6 1 ,
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1
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6 1 )
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6 2 ,
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2
( 6 2
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6
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6
X
1 1 ) Clue
THE ELDEST IS 9 YEARS OLD AND THE 2 YOUNGER ONES ARE 2 YEARS OLD. LET'S BREAK IT DOWN. THE PRODUCT OF THEIR AGES IS 36. SO THE POSSIBLE CHOICES ARE: 1,1,36 - SUM(1,1,36) = 38 1,6,6 - SUM(1,6,6) = 13 1,2,18 - SUM(1,2,18) = 21 1,3,12 - SUM(1,3,12) = 16 1,4,9 - SUM(1,4,9) = 14 2,2,9 - SUM(2,2,9) = 13 2,3,6 - SUM(2,3,6) = 11 3,3,4 - SUM(3,3,4) = 10 SIX OF THE SUMS ARE UNIQUE, SO IF IT WERE ONE OF THOSE, TOM WOULD HAVE RECOGNISED THE NUMBER ACROSS THE STREET THAT MATCHES AND HE WOULD KNOW THE ANSWER, BUT HE COULD NOT FIGURE OUT THE ANSWER. THIS MEANS THERE ARE TWO OR MORE COMBINATIONS WITH THE SAME SUM. FROM THE CHOICES ABOVE, ONLY TWO OF THEM ARE POSSIBLE NOW. 1,6,6 - SUM(1,6,6) = 13 2,2,9 - SUM(2,2,9) = 13 WHEN TOM HEARD THAT THE ELDEST IS VISITING HIS GRANDFATHER, WE CAN ELIMINATE COMBINATION 1 SINCE THERE ARE TWO ELDEST ONES. THIS LEAVES US WITH ONLY 1 OPTION LEFT, THAT IS 2, 2 AND 9 GRANDFATHER WAS 66 AND GRANDSON WAS 6. WHEN GRANDFATHER WAS 61, GRANSON WAS 1 (61 = 1 X 61) WHEN GRANDFATHER WAS 62, GRANSON WAS 2 (62 = 2 X 31) WHEN GRANDFATHER WAS 63, GRANSON WAS 3 (63 = 3 X 21) WHEN GRANDFATHER WAS 64, GRANSON WAS 4 (64 = 4 X 16) WHEN GRANDFATHER WAS 65, GRANSON WAS 5 (65 = 5 X 13) WHEN GRANDFATHER WAS 66, GRANSON WAS 6 (66 = 6 X 11) JOHN'S BIRTHDAY IS ON DECEMBER 31. TODAY IS JANUARY 1ST AND THE DAY BEFORE YESTERDAY IS DECEMBER 30. SO, THE DAY BEFORE YESTERDAY, JOHN WAS 17. YESTERDAY, HE TURNED 18. THIS YEAR, HE WILL TURN 19 AND NEXT YEAR, HE WILL TURN 20 THE ADDRESS IS 1460 SUNSET BOULEVARD. YOU KNOW THAT THE HOUSE NUMBERS ARE EVEN AND CONSECUTIVE, SO THEY MUST BE APPROXIMATELY 1/6TH THE VALUE OF THE SUM 8790. IN FACT, THE NUMBER THAT IS 1/6TH THE TOTAL IS THE MEAN (AVERAGE) FOR ALL 6 HOUSES. THE AVERAGE NUMBER IS 1465 (8790 / 6). THERE MUST BE 3 HOUSE NUMBERS GREATER THAN THAT NUMBER, AND 3 HOUSE NUMBERS LESS THAN THAT NUMBER, ALL BEING EVEN AND CONSECUTIVE. THEREFORE, THE 6 HOUSE NUMBERS ARE 1460, 1462, 1464, 1466, 1468, 1470. THE LOWEST HOUSE NUMBER, AS PER THE QUESTION, IS THE ANSWER: 1460