I don’t know who invented this game so if you know it please comment below and let me know so I can cite the source. I think I first saw it on a Spanish TV show from the network TVE.
The players are given a sequence of numbers and a target, for example:
1, 1, 2, 13, 25 → 20
(the target here is 20)
The goal is to produce the target number using only the sequence of numbers and basic mathematical operations (addition, subtraction, multiplication and division). Brackets (parentheses) can be used as much as needed. For example 1×((13+25)÷2)+1 is a solution to the puzzle above. Another solution is (25+13+1+1)÷2. Notice that it is required that each number is used exactly as many times as it appears in the sequence.
This is one of the few puzzles which you can create yourself in a second and still be almost sure it has a solution as long as you add a couple of small numbers to the sequence. And even when it doesn’t have a solution, it is a nice challenge to get as close to the target as possible. On the Spanish tv show the winner was whoever found the exact number first or the one with the best approximation when the time was over.
Below are some puzzles, all of which have at least one solution. Write your comments and solutions in the comment section and let us know if you have more puzzles :). Have fun!
1, 3, 12, 13, 23, 54 → 99
2, 4, 5, 10, 81 → 18
3, 9, 23, 23, 45 → 17
16, 25, 43, 80, 90 → 1
20, 41, 62, 83, 100 → 66
4, 6, 21, 32, 44, 60 → 12
The Hourly Puzzle 
Thanks for the fun little math learning game! Even the simplest games can provide great learning opportunities for younger kids during these summer brain drain months! If you’re looking for a more comprehensive K-2 math learning game, check out DreamBox Learning. Our online math game is a great way to supplement your kids classroom learning. Check out our two week free trial at http://www.dreambox.com. And thanks again for the great posting!
this was originally on a french tv show in the early 70’s
1,3,12,13,23,54-99=(54+(23+12+13)-3)
bonjour
Good share.
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I would like to see more posts like this
Thanks