Math Brain Teasers · Billy-B
Math Brain Teaser #10
From Billy-B's legendary 1001 Puzzle Collection — preserved on Puzz.com since 1998.
Puzzle #10
If the same functions are applied to reach the results in each of the three sets of numbers, find what number should replace the ? in the last set: 21 5 28 13 16 2 24 30 ? 17 7 25 7 10 8
Reveal Answer
30. In each set, the difference between the two leftmost numbers is divided by two, and then multiplied by the sum of the two rightmost numbers — The product is written in the middle for each set.
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