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Challenge 143

Ice Cream Promotion Difficulty Level: One summer, an ice cream factory held a promotion that included exchanging ten ice cream sticks for a stick ice cream. In this promotion, an ice cream stick corresponds to what fraction of the price of an ice cream? Challenge 142 Discover the King's Name Challenge Index Next >> Challenge 144 The Five Apples
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What is the difference between arrangement and combination?

A simple arrangement of n elements taken p through p, where n> = 1 and p is a natural number, is any ordering of p elements among n elements, where each way of taking the elements differs by the order and nature of the elements. That is, in arrangements also the order of the elements matters, while in combinations only the nature matters, that is, the elements must be different.
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Challenge 161

As many as possible Difficulty Level: What is the greatest number possible to write using only four numbers 1? Challenge 160 Watermelon in the Sun Challenge Index Next >> Challenge 162 Shaking Hands
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Challenge 190

Boy, girl and dog Difficulty level: A boy, a girl and a dog are weighed on a scale in three ways, as shown in the figure. How much would the three together weigh? Challenge 189 Fourth power plus four Challenge table Next >> Challenge 191 The boy, the sneakers and the whistles
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Pythagoras

"Pay attention: in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the collars. That is: a 2 = b 2 + c 2. Is that clear?" The teacher drops the chalk and turns to the class: "for this is the statement of the Pythagorean theorem. Now let's move on to the demonstration." As the teacher turns back to the blackboard, some students look at each other: "And who was this Pythagoras?
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Difficult Mathematical Challenges

Filter by difficulty level Very easy (8) Easy (49) Medium (96) Difficult (31) Very difficult (9) Displaying 31 challenges of level Difficult: [Remove filter] Challenge 8 On the old board game Challenge 17 Multiple of 1998 Challenge 18 Balls on the Straight Challenge 19 Form the Number 24 Challenge 24 Put the Soldiers in Lines Challenge 35 The Price of the Gift Challenge 43 How Many Eggs a Year?
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