The figure below is a regular pentagram. What is larger, the black area or the blue area?
A circle was inscribed in a square, and another square was inscribed in the circle. Which area is larger, the blue or the orange one?
In a square, the midpoints of its sides were marked and some segments were drawn. There is another square formed in the centre. Find its area, if the side of the square has length \(10\).
In a parallelogram \(ABCD\), point \(E\) belongs to the side \(AB\), point \(F\) belongs to the side \(CD\) and point \(G\) belongs to the side \(AD\). What is more, the marked red segments \(AE\) and \(CF\) have equal lengths. Prove that the total grey area is equal to the total black area.
Two numbers are given in terms of their prime factorizations: \(a= 2^3 \times 3^2 \times 5 \times 11^2 \times 17^2\) and \(b = 2 \times 5^2 \times 7^2 \times 11 \times 13\).
a) What is the greatest common divisor \(\mathrm{gcd}(a,b)\) of these numbers?
b) What is their least common multiple \(\mathrm{lcm}(a,b)\)?
c) Write down the prime factorization of \(\mathrm{gcd}(a,b) \times \mathrm{lcm}(a,b)\). Then write the prime factorization of \(a \times b\). What do you notice?
Little Jimmy visited his four aunties today. Each of them prepared a cake for him and his parents. Auntie Martha made a carrot cake, Auntie Camilla made a sponge, Auntie Becky made a chocolate cake and Auntie Anne made a fudge. Jimmy would like to visit the aunties the next time when aunties all make the same cakes again. Auntie Martha makes a carrot cake every two days, Auntie Camilla makes a sponge every three days, Auntie Becky makes a chocolate cake every four days and Auntie Anne makes a fudge every seven days. What day should he pick?
a) Two numbers, \(a\) and \(b\), are relatively prime. Their product is \(ab=3^5 \times 7^2\). What could these numbers be? Find all possibilities.
b) The gcd of two numbers, \(c\) and \(d\), is \(20\) and their product is \(cd=2^4 \times 5^3\). What could these numbers be? Find all possibilities.
Two numbers are \(a = 2 \times 3^5 \times 31^2 \times 7\) and \(b= 7^2 \times 2^4 \times 3^2 \times 29^2\). Find their greatest common divisor and least common multiple.
A valiant adventurer enters a dragon’s cave looking for the Holy Grail. She knows that Holy Grail is a chalice that is tall, made of gold, has encrusted rubies, and has an ancient inscription written on it. Upon entering, the knight discovers a long corridor of chalices, all marked with natural numbers starting from 1. He examines the first chalices and discovers, that every 10th chalice is tall, every 15th is made of gold, every 28th has encrusted rubies and every 27th has an ancient description. Assuming that is universally true for all the chalices in the cave, which chalice should the adventurer check so she doesn’t waste too much time checking all of them?
The gcd of the two numbers \(a\) and \(b\) is \(40\). What is their smallest possible product? How large can their product be?