If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?
what's the probability of getting a king or a queen from a pack of 52 cards?
A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?
You need to arrange three 7 and mathematical symbols to form number 1?
What makes this number unique: 8,549,176,320?
What are the 50th, 63rd and 100th numbers in the sequence below? 4, 5, 8, 8, 9, 9, 12, 13, 13, 13, 17, 18, ...
Can you arrange four 9's and use at most 2 math symbols, to make the total 100?
Find the combined weight of the Cat, Dog and Rabbit in the given picture.
I welcome the day with a show of light, I stealthily came here in the night. I bathe the earthy stuff at dawn, But by noon, alas! I'm gone.
How many letters are in the alphabet?
Which five letter word can be added at the end of below word to form a valid word? > Pin > Check > Boiling > View
There is a cryptic organization called Cicada 3301 that posts challenging puzzles online, possibly to recruit codebreakers and linguists.