81 x 9 = 801. What must you do to make the this equation true?

Replace the question mark with the correct number in below Picture:

What has 88 keys?

Solve the following series:
AZ, GT, MN, __, YB

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

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?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

A Child was born in Lahore, Pakistan.

Still child is not a Pakistani citizen.why ?