Fede chooses $50$ distinct integers from the set $\{1, 2, 3, \ldots, 100\}$ such that their sum equals $2900$. Determine the minimum number of even numbers that can be among the $50$ numbers chosen by Fede.

Let $n$ be a positive integer. There are $n$ colors available. Each of the integers from $1$ to $1000$ must be painted with one of the $n$ colors such that any two different numbers, if one divides the other, are painted in different colors. Determine the smallest value of $n$ for which this is possible.

Let $ABCD$ be a parallelogram with $\angle ABC = 105^\circ$. Inside the parallelogram, there is a point $E$ such that triangle $BEC$ is equilateral and $\angle CED = 135^\circ$. Let $K$ be the midpoint of side $AB$. Calculate the measure of $\angle BKC$.

Juli has a deck of $54$ cards and proposes the following game to Bruno. Juli places the cards in a row, some face-up and others face-down. Bruno can repeatedly perform the following move: select a card and flip it along with its two neighbors (turning face-up cards face-down, and vice versa for face-down cards). Bruno wins if, through this process, he manages to turn all the cards face up. Otherwise, Juli wins. Determine which player has a winning strategy and explain it. Note: When Bruno selects the first or the last card in the row, he flips only two cards. In all other cases, he flips three cards.

Around a circle, $20$ distinct positive integers are written. Alex divides each number by its neighbor, moving clockwise around the circle, and records the remainders obtained in each case. Teo performs a similar process but moves counterclockwise around the circle and records the remainders he obtains. If Alex finds only two distinct remainders among the $20$ he records, determine the number of distinct remainders Teo will record.

Find all integers $n > 1$ for which it is possible to fill the cells of an $n \times n$ grid with the integers from $1$ to $n^2$, without repetition, such that the average of the $n$ numbers in each row and each column is an integer.