What goes up but never comes down?

A girl was sitting in her hotel room when she heard a knock on the door. She opened the door and found that a man was standing outside. The man said, "Oh! I am really sorry, I thought this was my room." He then walked through the corridor to the elevator. The girl did not know the man. She closed her door and called security asking them to apprehend the man. What made her suspicious of that man? He might have been genuinely mistaken.

Solve the counting riddle by identifying the number of triangles in the given picture.

Find the next number in the series below

21 32 54 87 131 ?

How many letters are in the alphabet?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

Can you find out which options fits best with the missing column?

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?

During a secret mission, an agent gave the following code to the higher authorities
AIM DUE OAT TIE MOD

However, the information is in one word only and the rest are fake. To assist the authorities in understanding better, he also sent them a clue, If I tell you any one character of the code, you can easily find out the number of vowels in the codeword.

Can you find out the code word?

There is a hypothetical state between the USA and Mexico border 'Tango'.
Here 70 percent of the population have defective eyesight, 75 percent are hard of hearing, 80 percent have Nose trouble and 85 percent suffer from allergies, what percentage (at a minimum) suffer from all four ailments?