Find the next number in the sequence

1, 2, 6, 21, 88, __?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Find the number of squares in the below picture

Can you name four days which start with the letter 'T'?

When it is alive we sing, when it is dead we clap our hands. What is it?

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

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.

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.