100 doors in a row problem

There are 100 doors in a row numbered from 1 to 100. Initially all
are closed. Then you make 100 passes by the 100 doors. In pass 1 you
toggle the all the doors (1,2,3,4....)starting from the first door.
In the second pass you toggle every second door(2,4,6,8,...). In the
third pass you toggle all third doors (3,6,9...). Similarly you make
100 passes.

what state are the doors in after the last pass?

which are open which are closed??

Unusual paragraph

What is unusual about this paragraph? You will find that this is not
just an ordinary paragraph if you look at its words. An odd group of
words this is! Can you find what it is?

Golo is locked in a cave !!!

Golo is locked in a cave. He is having 2 vessels with him (5ltr & 7ltr).
The gate of the cave will open only when there are exactly 6 litres on
the handle. He can take as much water as he want from the nearby
water well. How he can make combinations such that the 7 ltr vessel
will have exactly 6 liters of water?

64 = 65 Geometry Paradox

Comparison of the areas of the 2 shapes creates a paradox: 64 = 65

How is this possible?

FORTY + TEN + TEN = SIXTY

Each of the letters in the equation below represents one of the
digits from 0 to 9. Determine which digit corresponds to each letter.

FORTY
+ TEN
+ TEN
-----
SIXTY

Race track problem

A Race track is one mile long, if a driver goes around once at
30 miles per hour, how fast must he drive in the second lap to
average sixty miles per hour over both laps?

Logic riddles

A horse have to transfer bananas from one point to the other point
(points are 1000km apart). He can take atmost 1000 bananas at a time
and he eats 1 banana after every km he travels. Tell me the
maximum no. of bananas he can take to the final point if the total
no. of bananas are 3000 ?