Avagadro's Number (How we count atoms)

Today in chemistry class, Mr Doktor taught us how to calculate how many atoms there in a mole of atoms using the Avagradro's number, we learn that:

-Atoms and molecules are extremely small
-Macroscopic bjects contain too many atoms to count or weigh individually
-Amedeo Avogadro proposed that the number of atoms in 12.00000g of carbon be equal to a constant
-This value is now called Avogadro's number and forms te basis of all quantitative chemistry
-1 mol= 6.02x10^23
-1 pair = 2, 1 dozen = 12, 1 century = 100, 1 mol= 6.02x10^23

e.g. a sample of carbon contains 2.47 x10^25 atoms. How many moles of carbon is this?