A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different. How do you measure 45 minutes?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

If 1+9+8=1, what is 2+8+9?

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?

Can you move 2 matchsticks to form four equal sized squares.

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

O_er_t_o_

Complete the missing letters of the given word.