Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

How do you go from 98 to 720 using just one letter?

Can you make the below equation true by using any three numbers from "1, 3, 5, 7, 9, 11, 13 and 15"?

( ) + ( ) + ( ) = 30

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

I don't get anymore wetter, no matter how much rain falls on me.

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

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Make a sentence consisting of three words that have the whole alphabet.

What is full of holes but still holds water?

Find the next number in the series below

21 32 54 87 131 ?