You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

Can you find the least possible number such that

If the number is divided by 3, it gives the remainder of 1;
If the number is divided by 4, it gives the remainder of 2;
If the number is divided by 5, it gives the remainder of 3;
If the number is divided by 6, it gives the remainder of 4.

What kind of band never plays music?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

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?

I have no life, but I can die. What am I?

I have branches, but no fruit, trunk or leaves. What am I?

what's the probability of getting a king or a queen from a pack of 52 cards?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

What word is pronounced the same if you take away four of its five letters?