Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

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

It belongs to you, but other people use it more than you do. What is it?

1. Where does Easter come from before Valentine's Day?

2. Do you know what is in the middle of Valentine's?

3. What did the lady bee say to the man bee on the occasion of Valentine's Day

The chance of Mr John winning the lottery is 10%. All participants lined up and Mr John is 4th in the row. The first three participants lose the lottery.

What is the chance of Mr John now?

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

Alex opened 24 presents
Jonah opened 8 presents
Clara opened 1 present

Can you find out how many presents were opened by Candy?

One night, a man runs away from home. He turns left and keeps running. After some time he turns left again and keeps running. Later, he turns left one more time and runs back home—but when he gets home, he finds a man in a mask. Who was the man in the mask?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?