Where do you go to learn how to make ice cream?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

Can you count the number of lines in the below picture?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

You are given with the following sum. Each of the letters can be decoded as a digit. If we tell you that D = 5, then can you solve it entirely?

DONALD
+GERALD
=ROBERT

There are three Athletes (John, Tarun and Harish) and their individual Coaches (Jacob, Meenaxi and Priyanka) standing on the shore.
No Coach trusts their Athlete to be near any other Coach unless they are also with them.
There is a boat that can hold a maximum of two persons.
How can the six people get across the river?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I am an odd number. Take away a letter and I become even. What number am I?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

In my garden, I have many trees but only one of them is the mango tree. In these mango trees, there are some mangoes(as expected).

But after a strong wind, there are neither mangoes on the tree nor on the ground. Explain?