Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

I have 50 feet long of cloth, I need to create 50 handkerchiefs each size of 1 foot. I take one minute to cut a 1-foot handkerchief. So how long will it take to cut 50 handkerchiefs?

Replace the question mark with the correct number in the below-given picture?

I look at you, you look at me I raise my right, you raise your left. What am I?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

If six children and two dogs were under an umbrella, how come none of them got wet?

You have a square. What you have to do is cut and reassemble the square such that you create a Red Cross sign that has the same volume as that of the square.