How do you write 23 using only the number 2?
34 using only the number 3?
56 using only the number 5?
100 using only the number 9?

Answer:

By using fractions. 22+2/2=23, 33+3/3=34, 55+5/5=56, 99+9/9=100

Try another Brain Teaser:

Take a look at all these numbers: 66, 22, 99, 33, 44, 55. What number greater than 1 can be divided into all these numbers without leaving a remainder?