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?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Why Aeroplane windows are round?

How many times in a given day, minutes and hour clock comes in a straight line ?

Can you find the dog hidden in a group of pandas?

I know a nine-letter word having only one vowel.
Do you ?

Joseph buys three kinds of chocolates for 100 rupees. The first one is priced at 5 rupees, second one at 3 rupees and third one at 0.5 rupees.

If he bought 100 chocolates in total, how many pieces do you think he bought each chocolate?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?