How many words can a pen with half refill write?

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

Can you move 2 matchsticks to form four equal sized squares.

Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

Can you replace the question mark with the correct number?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

You have $100 with you and you have to buy 100 balls with it. 100 is the exact figure and you can't go below or above the numbers and you have to use the entire $100. If there is no kind of tax applied how many of each of the following balls will you be able to buy:

Green Balls costing $6
Yellow Balls costing $3
Black Balls costing $0.10

Now, how many of each must you buy to fulfil the condition given?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

The dirtier I get, the whiter I look. Who am I?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?