Number relationships

21 is to 64, and 7 is to 22. What is 12 to?

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The answer is E. Two examples are given so that the rule is certain. 21 became 64 and 7 became 22: in both, the first number has been multiplied by 3, then 1 added. One example alone would not be enough — 21 to 64 could just as easily be adding 43, but that does not work for 7. Doing the same to 12 gives 37. Work out your answer before you look at the choices, so a near miss cannot tempt you.

14 is to 43, and 24 is to 73. What is 17 to?

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The answer is C. Two examples are given so that the rule is certain. 14 became 43 and 24 became 73: in both, the first number has been multiplied by 3, then 1 added. One example alone would not be enough — 14 to 43 could just as easily be adding 29, but that does not work for 24. Doing the same to 17 gives 52. Work out your answer before you look at the choices, so a near miss cannot tempt you.

24 is to 50, and 29 is to 60. What is 26 to?

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The answer is D. Two examples are given so that the rule is certain. 24 became 50 and 29 became 60: in both, the first number has been doubled, then 2 added. One example alone would not be enough — 24 to 50 could just as easily be adding 26, but that does not work for 29. Doing the same to 26 gives 54. Check whether something small was added or taken away after the multiplying.

11 is to 33, and 17 is to 51. What is 24 to?

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The answer is D. Two examples are given so that the rule is certain. 11 became 33 and 17 became 51: in both, the first number has been multiplied by 3. One example alone would not be enough — 11 to 33 could just as easily be adding 22, but that does not work for 17. Doing the same to 24 gives 72. Work out your answer before you look at the choices, so a near miss cannot tempt you.

16 is to 32, and 17 is to 34. What is 29 to?

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The answer is E. Two examples are given so that the rule is certain. 16 became 32 and 17 became 34: in both, the first number has been doubled. One example alone would not be enough — 16 to 32 could just as easily be adding 16, but that does not work for 17. Doing the same to 29 gives 58. Work out your answer before you look at the choices, so a near miss cannot tempt you.

13 is to 26, and 8 is to 16. What is 27 to?

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The answer is C. Two examples are given so that the rule is certain. 13 became 26 and 8 became 16: in both, the first number has been doubled. One example alone would not be enough — 13 to 26 could just as easily be adding 13, but that does not work for 8. Doing the same to 27 gives 54. Check whether something small was added or taken away after the multiplying.

28 is to 16, and 12 is to 8. What is 10 to?

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The answer is E. Two examples are given so that the rule is certain. 28 became 16 and 12 became 8: in both, the first number has been halved, then 2 added. One example alone would not be enough — 28 to 16 could just as easily be adding -12, but that does not work for 12. Doing the same to 10 gives 7. If doubling does not fit, try trebling, then halving.

25 is to 51, and 9 is to 19. What is 23 to?

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The answer is B. Two examples are given so that the rule is certain. 25 became 51 and 9 became 19: in both, the first number has been doubled, then 1 added. One example alone would not be enough — 25 to 51 could just as easily be adding 26, but that does not work for 9. Doing the same to 23 gives 47. Say what happened to the first number out loud before you touch the second.

7 is to 14, and 27 is to 54. What is 25 to?

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The answer is E. Two examples are given so that the rule is certain. 7 became 14 and 27 became 54: in both, the first number has been doubled. One example alone would not be enough — 7 to 14 could just as easily be adding 7, but that does not work for 27. Doing the same to 25 gives 50. Work out your answer before you look at the choices, so a near miss cannot tempt you.

12 is to 22, and 17 is to 32. What is 25 to?

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The answer is A. Two examples are given so that the rule is certain. 12 became 22 and 17 became 32: in both, the first number has been doubled, then 2 taken away. One example alone would not be enough — 12 to 22 could just as easily be adding 10, but that does not work for 17. Doing the same to 25 gives 48. Say what happened to the first number out loud before you touch the second.

6 is to 16, and 23 is to 67. What is 7 to?

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The answer is A. Two examples are given so that the rule is certain. 6 became 16 and 23 became 67: in both, the first number has been multiplied by 3, then 2 taken away. One example alone would not be enough — 6 to 16 could just as easily be adding 10, but that does not work for 23. Doing the same to 7 gives 19. Work out your answer before you look at the choices, so a near miss cannot tempt you.

28 is to 83, and 23 is to 68. What is 8 to?

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The answer is A. Two examples are given so that the rule is certain. 28 became 83 and 23 became 68: in both, the first number has been multiplied by 3, then 1 taken away. One example alone would not be enough — 28 to 83 could just as easily be adding 55, but that does not work for 23. Doing the same to 8 gives 23. Check whether something small was added or taken away after the multiplying.

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