Six superheroes capture 20 villains. The first captures 1, the second 2, the third 3. The fourth captures more than each of the other five. What is the smallest possible number captured by the fourth?
Inside the cube is an opaque solid pyramid ABCDS with base ABCD. Its apex S is the midpoint of the indicated cube edge. Viewed from above, below, behind, in front, right and left, which drawing never occurs?
A circular carpet lies on a floor of equal square tiles. Every tile with at least one point in common with the carpet is grey. Which outcome is impossible?
For a function on the integers, consider: “For every even x, f(x) is even.” What is its negation? Editorial note: printed option D omits the condition “x is even”. For this self-study item D is scored only with that explicitly restored condition; all printed choices below are preserved.
A box contains the 900 distinct cards numbered 100 to 999. Franz draws cards and finds each digit sum. At least how many must he draw to guarantee three with equal digit sums?