Hard Riddles With Hints and Answers

A camera needs me before the picture is sharp; a meeting loses me when every phone starts buzzing. What am I?

A lawyer builds me with facts, doubt weakens me, and proof can make me strong again. What am I?

I begin with two premises and end with a conclusion; if my middle term fails, so do I. What am I?

Scientists trust me only after trying to prove me wrong; assume me without testing and I am just a guess. What am I?

You can count along me, divide me, make me negative, and still never reach my final member. What am I?

Eight is correct after five plus three, wrong after five times three, and meaningless on a blank page. What am I?

I find cracks before publication, improve an argument by pressing its weak points, and work best when the attack is fair. What am I?

Write me in a diary and I am ahead of you; wake up inside me and everyone calls me today. What am I?

Ten seconds before midnight I make a room loud; ten seconds before an exam I make it silent. Same numbers, different feeling. What am I?

I arrive slowly through kept promises, leave quickly after one public lie, and often enter the room before you do. What am I?

A violin string needs enough of me to sing; a room after an argument can have too much of me, even in silence. What am I?

Court records, photographs and scars can show me. Apologies may change my meaning, but not my events. What am I?

What comes next: 3, 5, 9, 17, 33, ?

What comes next: 1, 3, 6, 10, 15, ?

What comes next: 1A, 2B, 4D, 8H, ?

One brick weighs 1 kg plus half a brick. How much does one brick weigh?

A parent is 36 and a child is 9. In how many years will the parent be three times the child's age?

You have 8 coins made of 10p and 20p coins. The total is £1.20. How many 20p coins are there?

A cube is painted on all sides and cut into 27 equal smaller cubes. How many small cubes have paint on exactly one face?

What is the maximum number of pieces from 3 straight cuts across a round cake, if each cut crosses all previous cuts inside the cake?

You have a 5-litre jug and a 3-litre jug. How can you measure exactly 4 litres?