Eight of us go fourth, not back, to protect our king from an attack. What are we?

O_er_t_o_

Complete the missing letters of the given word.

No matter how little or how much you use me, you change me every month. What am I?

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

People put me on the table and cut me but do not eat me. What am I?

What brings you down but never up?

There is a hypothetical state between the USA and Mexico border 'Tango'.
Here 70 percent of the population have defective eyesight, 75 percent are hard of hearing, 80 percent have Nose trouble and 85 percent suffer from allergies, what percentage (at a minimum) suffer from all four ailments?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

1 dollar = 100 cent
= 10 cent x 10 cent
= 1/10 dollar x 1/10 dollar
= 1/100 dollar
= 1 cent

=> 1 dollar = 1 cent

solve this tricky problem?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?