# Mathematical Olympiad - practice problems

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

- Circumferences 83111

Péta composed several planar shapes from mutually congruent triangles. The circumferences of the first three are 8 cm, 11.4 cm, and 14.7 cm, respectively. Determine the perimeter of the fourth shape. - Characters 82998

Adam wrote the following sum with five secret adders: a + bb + ccc + dddd + eeeee. He revealed that the characters "a, b, c, d, e" represent the different digits 1, 2, 3, 4, and 5 and that the resulting sum is divisible by 11. Which is the smallest and wh - Determine 82724

A right triangle has an area of 36 cm². A square is placed in it so that two sides of the square are parts of two sides of a triangle, and one vertex of the square is in a third of the longest side. Determine the area of this square. - Quadrilateral 82616

Triangle ABC is divided into line segments. Lines DE and AB are parallel. Triangles CDH, CHI, CIE, and FIH have the same area, namely 8 dm². Find the area of quadrilateral AFHD.

- Two-digit 82521

Karel had to multiply two two-digit numbers. Out of care, he changed the order of the digits in one of the factors and got a product that was 4,248 less than the correct result. What is the correct result? How much should Karl have earned? - Department 82388

Last year, there were 30 more boys than girls in our scout troop. This year, the number of children in the ward increased by 10%, while the number of boys increased by 5% and the number of girls increased by 20%. How many children do we have in the depart - Subtract 82333

I think of three numbers; when I add them, I get 16; when I subtract the third from the sum of the first two numbers, I get 10; when I subtract the second from the sum of the first and third numbers, I get 8. Which numbers do I think? - Quadrilateral calc

The square ABCD is given. The midpoint of AB is E, the midpoint of BC is F, CD is G, and the midpoint of DA is H. Join AF, BG, CH, and DE. Inside the square (approximately in the middle), the intersections of these line segments form a quadrilateral. Calc - Respectively 81293

The figure shows the squares ABCD, EFCA, CHCE, and IJHE. Points S, B, F, and G are, respectively, the centers of these squares. Line segment AC is 1 cm long. Determine the area of triangle IJS. Please help...

- Intersection 81017

There are also two equilateral triangles ABC, and BDE, such that the size of the angle ABD is greater than 120° and less than 180° points C and E lie in the same half-plane defined by the line AD. The intersection of CD and AE is marked F. Determine the s - Respectively 80982

The vertices of the square ABCD are joined by the broken line DEFGHB. The smaller angles at the vertices E, F, G, and H are right angles, and the line segments DE, EF, FG, GH, and HB measure 6 cm, 4 cm, 4 cm, 1 cm, and 2 cm, respectively. Determine the ar - Double-digit 80970

Eva thought of two natural numbers. She first added these correctly, then subtracted them correctly. In both cases, she got a double-digit result. The product of the resulting two-digit numbers was 645. Which numbers did Eva think of? Please, what is this - SKMO

Petra had written natural numbers from 1 to 9. She added two of these numbers, deleted them, and wrote the resulting sum instead of the summaries. She thus had eight numbers written down, which she managed to divide into two groups with the same product. - Three-digit 80768

Nikola had one three-digit and one two-digit number written in her notebook. Each of these numbers was made up of different digits. The difference in Nicole's numbers was 976. What was their sum?

- Originally 80757

There were 45 sheep and several shepherds in the meadow. After half of the shepherds and a third of the sheep left the meadow, the remaining shepherds and sheep had a total of 126 legs. All sheep and all shepherds usually had leg counts. how many shepherd - Grandchildren 80639

The average age of the grandfather, grandmother, and their five grandchildren is 26 years. The average age of the grandchildren themselves is 7 years. Grandma is a year younger than grandpa. How old is grandma? - Smallest z9

Find the smallest positive numbers a and b for which 7a³ = 11b⁵ - Positive integer integral

How many different sets of a positive integer in the form (x, y, z) satisfy the equation xyz=1400? - Differences 80551

Bolek and Lolek each had their own arithmetic sequence. Both Lolek and Bolek's sequence started with the number 2023 and ended with the number 3023. The two sequences had 26 numbers in common. The ratio of Bolek's and Lolka's difference was 5:2. What is t

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