You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Why do we preferably have round manhole covers and not square ones?

A man hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight?

Name the three-letter word that can complete the below words:

A) L O _ _ _ E
B) E D U _ _ _ E
C) _ _ _ E R
D) _ _ _ T L E

What is the next number in this matchsticks series riddle?

What number comes next in this sequence:
7 8 5 5 3 4 4 _

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

Can you find the next number in the below sequence
3 , 7 , 10 , 11 , 12 , 17 ?

Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1