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Math Problems for children from 5 to 15 [pdf] by V I Arnold

53 minutes ago

Created a post 62 points @sebg

Math Problems for children from 5 to 15 [pdf] by V I Arnold

@ordu 18 minutes

Replying to @sebg 🗣

The problem #13, mentioned in the introduction, is said to be really tough for academicians, but I'm not! Probably I'm just plain stupid.

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@imvetri 18 minutes

Replying to @sebg 🗣

When child labour is illegal, Why shouldn't be child education.

We are born with natural skills, mainstream education ruins originality.

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@LeifCarrotson 15 minutes

Replying to @sebg 🗣

They're interesting to adults, too! Simple enough that it feels like you should be able to blurt out the answer, I'm more than twice the maximum recommended age and a professional engineer, but (at least for me) it takes some thought. The top recommended three:

> 1. Masha was seven kopecks short to buy a first reading book, and Mishalacked one kopeck. They combined their money to buy one book to share, but even then they did not have enough. How much did the book cost?

> 3. A brick weighs one pound and half the brick. How many pounds does the brick weigh?

> 13. Two volumes of Pushkin, the first and the second, are side-by-side on a bookshelf. The pages of each volume are 2 cm thick, and the cover – front and back each – is 2 mm. A bookworm has gnawed through (perpendicular to the pages) from the first page of volume 1 to the last page of volume 2. How long is the bookworm’s track?

I do take objection to the answer to question 13 - the author seems particularly set on one way of loading the bookshelves as correct.

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@rdtsc 11 minutes

Replying to @sebg 🗣

> The hypotenuse of a right-angled triangle (in a standard American examination) is 10 inches, the altitude dropped onto it is 6 inches. Find the area of the triangle. American school students had been coping successfully with this problem over a decade. But then Russian school students arrived from Moscow, and none of them was able to solve it as had their American peers (giving 30 square inches as the answer). Why?

That's a good one. I know the answer but won't reveal it since it's a fun one to discover yourself.

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@kangnkodos 5 minutes

Replying to @sebg 🗣

#18 is impossible. This margin is too small to provide the proof.

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@waynesonfire 5 minutes

Replying to @sebg 🗣

> 3. A brick weighs one pound and half the brick. How many pounds does the brick weigh?

huh? Good luck 5 year old. This is how you get kids to hate math.

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@agentultra 5 minutes

Replying to @sebg 🗣

Another interesting book in this vein if these problems tickle your fancy: https://www.amazon.ca/Math-Three-Seven-Mathematical-Preschoo...

Working on math problems together with your kids is a fun way to learn how they think and reason. It has led me to have a deeper emotional connection with my kids as I learn what they struggle with in school. I have slowly learned that some times framing the problem a certain way helps them to grasp what is being taught better than brute-forcing them through exercises and homework.

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@SeanLuke 23 minutes

Replying to @sebg 🎙

First question:

> 1. Masha was seven kopecks short to buy a first reading book, and Misha lacked one kopeck. They combined their money to buy one book to share, but even then they did not have enough. How much did the book cost?

My goodness, that's an impressive 5 year old.

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@rcoumet 22 minutes

Replying to @sebg 🎙

> Vasya has 2 sisters more than he has brothers. How many daughters more than sons do Vasya’s parents have?

In a world of gender and pronouns fluidity, does this even have an answer ?

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