Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

Replace the question mark with the correct number in below Picture:

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

Find out the missing number in the picture attached:

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

A Shopkeeper collects 71 rupees in the form of 20 paisa and 25 paisa.
He collects a total of 324 coins.

Can you tell me how many number of 20-paisa and 25-paisa he got?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?