BrainBashers - Brain Teasers and Puzzles

Puzzle 729

My shirt has 5 buttons, my cardigan has 2 buttons, and my suit jacket has no buttons.

How many buttons do my trousers have?

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Puzzle 730

Sam takes 20 days to build a wall.

Taylor and Kelly each take 10 days to build a wall.

How long will it take the three of them to build a wall if they work together?

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Puzzle 731

What is the smallest positive integer, which, when multiplied by 6 …

… gives a number consisting of only 8's?

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Puzzle 732

Which four-letter word can be placed between the two following words to make two new words:
arm[----]stand

In the following example, the word 'book' creates the words 'cookbook' and 'bookcase'.
cook[book]case

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