Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

In the image given, you can find several triangles. Can you count them all?

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?

Your job is to measure 45 minutes if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

What is next number in the pattern below:

131 517 192 123 ?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

In the four images below, can you find the odd one out?

Replace the question mark with the correct number in below Picture: