Find the next number in the sequence

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

When can we add 2 to 11 and get 1 as the correct answer?

What's a single-digit number with no value?

We have arranged an array of numbers below. What you have to do is use any kind of mathematical symbol you know excluding any symbol that contains a number like cube root. You can use any amount of symbols but you have to come up with a valid equation for all of them.

0 0 0 = 6
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

Count the number of balls in picture below:

With the help clues provided in the image, can you find the 5 digit key?

In the figure, you can see nine stars. What you have to do is connect all of them by using just four line and without lifting your hand i.e. in a continuous flow.

People put me on the table and cut me but do not eat me. What am I?

After a heavy Thanksgiving meal, the night watchman went to work. In the morning, he told his boss he had dreamed that a saboteur planted a bomb in the factory and that he felt it was a warning. The boss promptly fired him. Worker confused, Why boss fire him?