I am a two-digit whole number. My tens digit is twice as large as my units digit. When you add my two digits together, the sum is 9. What number am I?

A wall clock strikes once at 1 o'clock, twice at 2 o'clock, and so on, up to twelve times at 12 o'clock. It also strikes exactly once at every half-hour mark (e.g., 1:30, 2:30). How many total strikes does it make between 12:15 PM and 3:45 PM on the same afternoon?

Three friends check into a hotel room that costs $30 total, so they each pay $10. Later, the manager realizes there was a mistake and the room should only cost $25. He gives $5 to the bellhop to return to the guests. The dishonest bellhop pockets $2 for himself and gives $1 back to each of the three friends. Now, each friend has paid $9 (total $27), and the bellhop has $2, which equals $29. Where is the missing $1?

Three boxes are labeled: Box 1 ('The $100 is in this box'), Box 2 ('The $100 is not in this box'), and Box 3 ('The $100 is not in Box 1'). If at most one of the three statements is true, which box contains the $100?

If five cats can catch five mice in five minutes, how many minutes does it take for one cat to catch one mouse?

Four people need to cross a dark bridge at night with only one flashlight. The bridge holds at most two people at a time, and any crossing requires the flashlight. Person A takes 1 minute to cross, B takes 2 minutes, C takes 7 minutes, and D takes 10 minutes. Pairs walk at the speed of the slower person. What is the minimum time needed for all four to cross?

Four runners—Anna, Ben, Cole, and Dana—finished a race. Anna finished before Ben. Cole did not finish first or last. Dana finished immediately after Ben. Who won the race?