If eleven plus two equals one, what does nine plus five equal?

Find the missing number in the image below.

Where do you go to learn how to make ice cream?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

A four-digit number (not beginning with 0) can be represented by ABCD. There is one number such that ABCD=A^B*C^D, where A^B means A raised to the B power. Can you find it?

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

How many letters are in the alphabet?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?