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

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

AB * C = DE - F = GH / I

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

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

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

Can you find out the remainder when 3^300 is divided by 5?

In a classic wine shop, the list of three most popular wines are:
- The cost of 1 French wine bottle: 500$
- The cost of 1 German wine bottle: 100$
- The cost of 20 Dutch wine bottles: 100$

John entered the wine shop and he needs to buy
- All three types of wine bottles.
- Needs to buy Dutch wine bottles in multiples of 20.
- Need to buy 100 wine bottles in total.

John has only 10000$. How many wine bottles of each type, John must buy?

A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day and a half. How many hens does the farmer need to produce one dozen eggs in six days?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?