Enjoy Your Ageless Mental Agility • 265
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5. a b c d
?
6. a b c d
?
7. a b c d
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8. a b c d
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9. 1, 13, 25, 37,
a b
10. ?
c d
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11. a b c d
X XX XX XX XX XX XX XX a XX b X c XX d XX
X XX, ? XX, X XX XX XX X XX
12.
X XX X XX X
X
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13. a b c d
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14. 1, 2, 3, 5, 7, 10