A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.

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

Find out a multi-digit number that if multiplied by the number 9 or any of its multiplications products (i.e. 18, 27, 36, 45,..) will result in the multiplication factor repeated (n) number of times.

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

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

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

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?

How many triangles are there in the picture below?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?