Mathematical Olympiad - practice problems - page 3 of 9
MO tasks are not easy, even for adults. At the same time, we believe that the right solution, which is here published almost on one click will serve as the inspiration.Do not be discouraged if you did not discover the right solution. Experiment, sketching, "play" with the problem. Sometimes it helps to look into a book and find out similar problems resolved. Sometimes help three days pause, and then you found the right solution.
Direction: Solve each problem carefully and show your solution in each item.
Number of problems found: 162
- Subtract 10001
For five whole numbers, if we add one to the first, multiply the second by the second, subtract three from the third, multiply the fourth by four, and divide the fifth by five, we get the same result each time. Find all five of the numbers that add up to
- The king
The king divided ducats among his sons. He gave the eldest son a certain number of ducats, gave the younger one ducat less, gave the other one ducat less, and proceeded to the youngest. Then he returned to his eldest son, gave him one ducat less than a wh
- Twos
Vojta started writing the number this year, 2019202020192020, into the workbook. And so he kept going. When he wrote 2020 digits, he no longer enjoyed it. How many twos did he write?
- Circumference 9811
Kristýna chose a certain odd natural number divisible by three. Jakub and David then examined triangles with a circumference in millimeters equal to the number selected by Kristýna and whose sides have lengths in millimeters expressed by different integer
- Between two bus stops
Wanda lives between two bus stops at three-eighths of their distance. He started the house today and found that he would have arrived at the bus stop if he had run to one or the other. The average bus speed is 60 km/h. What is Wanda's average running spee
- Complaining 9611
Ondra, Mathias, and Kuba are returning from collecting nuts. They have a total of 120. Mathias complains that Ondra has the most, as always. The father orders Ondra to sprinkle it on his Mathias so that the number of nuts doubles. Now Cuba is complaining
- Three-digit 9601
Majka researched multi-digit numbers, in which odd and even numbers alternate regularly. Those who start with an odd number are called comics, and those who start with an even number are called cheerful. (For, number 32387 is comic, and number 4529 is hil
- Matemakak 9432
The cookbook by Matěj Matemakak says: The greatest common divisor of flour weight and sugar weight is 15, the greatest common divisor of sugar weight and lemon peel weight is 6, the product of sugar weight and lemon peel weight is 1800, and the smallest c
- Sufficient 9391
In Kocourkov, they use coins with only two values expressed in Kocourkov crowns by positive integers. With a sufficient number of such coins, it is possible to pay any integer amount greater than 53 cats’ crowns accurately and without return. However, we
- Divisible 9331
The number X is the smallest natural number whose half is divisible by three, a third is divisible by four, a quarter is divisible by eleven, and its half gives a remainder of 5 when divided by seven. Find this number.
- Identical 8831
In triangle ABC, point P lies closer to point A in the third of line AB, point R is closer to point P in the third of line P, and point Q lies on line BC, so the angles P CB and RQB are identical. Determine the ratio of the area of the triangles ABC and P
- Determine 8611
Determine all natural numbers A and B pairs for which the sum of twice the least common multiple and three times the greatest common divisor of natural numbers A and B is equal to their product.
- Solutions 8481
For which integers x is the ratio (x + 11) / (x + 7) an integer? Find all solutions.
- Justification 8468
The natural number n has at least 73 two-digit divisors. Prove that one of them is the number 60. Also, give an example of the number n, which has exactly 73 double-digit divisors, including a proper justification.
- Luggage and air travel
Two friends traveling by plane had a total of 35 kg of luggage. They paid one 72 CZK and the second 108 CZK for being overweight. If only one paid for all the bags, it would cost 300 CZK. What weight of baggage did each of them have? How many kilograms of
- Self-counting machine
The self-counting machine works exactly like a calculator. The innkeeper wanted to add several three-digit natural numbers on his own. On the first attempt, he got the result in 2224. To check, he added these numbers again, and he got 2198. Therefore, he
- Six-digit primes
Find all six-digit prime numbers that contain each one of digits 1,2,4,5,7, and 8 just once. How many are there?
- Restriction 7442
The figure shows two rows of hexagonal boxes that continue to the right without restriction. Fill in one field with one positive integer so that the product of the numbers in any three adjacent fields is 2018. Determine the number that will be in the top
- Inequality 7320
Let a, b, and c be positive real numbers whose sum is 3, each of which is at most 2. Prove that the inequality holds: a2 + b2 + c2 + 3abc
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