Number analogies

(12 [72] 6) (9 [45] 5) (11 [?] 11) What number belongs in the brackets?

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The answer is C. Use the two complete sets to find the rule, then check it before you use it. In the first, 12 and 6 give 72; in the second, 9 and 5 give 45. In both, the number in the brackets is the two outside numbers multiplied together. Doing the same to 11 and 11 gives 121. Look at the size of the number in the brackets: much bigger than the outside numbers usually means multiplying.

(3 [18] 6) (9 [108] 12) (7 [?] 7) What number belongs in the brackets?

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The answer is D. Use the two complete sets to find the rule, then check it before you use it. In the first, 3 and 6 give 18; in the second, 9 and 12 give 108. In both, the number in the brackets is the two outside numbers multiplied together. Doing the same to 7 and 7 gives 49. Look at the size of the number in the brackets: much bigger than the outside numbers usually means multiplying.

(12 [16] 4) (12 [21] 9) (12 [?] 3) What number belongs in the brackets?

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The answer is D. Use the two complete sets to find the rule, then check it before you use it. In the first, 12 and 4 give 16; in the second, 12 and 9 give 21. In both, the number in the brackets is the two outside numbers added together. Doing the same to 12 and 3 gives 15. If adding does not work, try multiplying, then try taking one from the other.

(4 [11] 7) (3 [10] 7) (3 [?] 12) What number belongs in the brackets?

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The answer is D. Use the two complete sets to find the rule, then check it before you use it. In the first, 4 and 7 give 11; in the second, 3 and 7 give 10. In both, the number in the brackets is the two outside numbers added together. Doing the same to 3 and 12 gives 15. Write the rule down in words before you work out the answer.

(3 [18] 6) (2 [22] 9) (5 [?] 12) What number belongs in the brackets?

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The answer is D. Use the two complete sets to find the rule, then check it before you use it. In the first, 3 and 6 give 18; in the second, 2 and 9 give 22. In both, the number in the brackets is the two outside numbers added together and then doubled. Doing the same to 5 and 12 gives 34. If adding does not work, try multiplying, then try taking one from the other.

(7 [42] 6) (9 [63] 7) (9 [?] 10) What number belongs in the brackets?

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The answer is B. Use the two complete sets to find the rule, then check it before you use it. In the first, 7 and 6 give 42; in the second, 9 and 7 give 63. In both, the number in the brackets is the two outside numbers multiplied together. Doing the same to 9 and 10 gives 90. Write the rule down in words before you work out the answer.

(4 [8] 4) (2 [11] 9) (7 [?] 9) What number belongs in the brackets?

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The answer is A. Use the two complete sets to find the rule, then check it before you use it. In the first, 4 and 4 give 8; in the second, 2 and 9 give 11. In both, the number in the brackets is the two outside numbers added together. Doing the same to 7 and 9 gives 16. Look at the size of the number in the brackets: much bigger than the outside numbers usually means multiplying.

(6 [24] 6) (10 [30] 5) (3 [?] 11) What number belongs in the brackets?

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The answer is C. Use the two complete sets to find the rule, then check it before you use it. In the first, 6 and 6 give 24; in the second, 10 and 5 give 30. In both, the number in the brackets is the two outside numbers added together and then doubled. Doing the same to 3 and 11 gives 28. Always test your rule on the second set before using it on the third.

(8 [4] 4) (8 [5] 3) (8 [?] 2) What number belongs in the brackets?

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The answer is B. Use the two complete sets to find the rule, then check it before you use it. In the first, 8 and 4 give 4; in the second, 8 and 3 give 5. In both, the number in the brackets is the two outside numbers the right number taken from the left one. Doing the same to 8 and 2 gives 6. Always test your rule on the second set before using it on the third.

(6 [48] 8) (5 [15] 3) (7 [?] 10) What number belongs in the brackets?

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The answer is A. Use the two complete sets to find the rule, then check it before you use it. In the first, 6 and 8 give 48; in the second, 5 and 3 give 15. In both, the number in the brackets is the two outside numbers multiplied together. Doing the same to 7 and 10 gives 70. Look at the size of the number in the brackets: much bigger than the outside numbers usually means multiplying.

(6 [36] 12) (12 [46] 11) (9 [?] 2) What number belongs in the brackets?

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The answer is E. Use the two complete sets to find the rule, then check it before you use it. In the first, 6 and 12 give 36; in the second, 12 and 11 give 46. In both, the number in the brackets is the two outside numbers added together and then doubled. Doing the same to 9 and 2 gives 22. Look at the size of the number in the brackets: much bigger than the outside numbers usually means multiplying.

(3 [24] 8) (4 [36] 9) (3 [?] 3) What number belongs in the brackets?

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The answer is A. Use the two complete sets to find the rule, then check it before you use it. In the first, 3 and 8 give 24; in the second, 4 and 9 give 36. In both, the number in the brackets is the two outside numbers multiplied together. Doing the same to 3 and 3 gives 9. If adding does not work, try multiplying, then try taking one from the other.

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Number analogies

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