Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

What is the largest number you can write with just 3 digits?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

What number divided by 4 is the same as that number minus 4?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

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