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

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

Next Number in the Series,

5, 16, 49, 104, ?

In Greek mythology, the Sphinx sat outside of Thebes and asked this riddle of all travellers who passed by. If the traveller failed to solve the riddle, then the Sphinx killed him/her. And if the traveller answered the riddle correctly, then the Sphinx would destroy herself. The riddle:

What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?

Oedipus solved the riddle, and the Sphinx destroyed herself.

Before reading ahead, you must know the fact that only one of the people here is telling the truth.

A says that B is lying.
B says that C is lying.
C says both A and B are lying.

Can you find out who is speaking the truth?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

What is the fastest way to double your money?