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

I have 50 feet long of cloth, I need to create 50 handkerchiefs each size of 1 foot. I take one minute to cut a 1-foot handkerchief. So how long will it take to cut 50 handkerchiefs?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

If you had an infinite supply of water and 5-quart and 3-quart pails, how would you measure exactly 4 quarts? What is the least number of steps you need?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

I have Rs.50 and I spend it in the way as below.