4.10 g C12H22O11 * ( 1 mol / 342.2965 g ) * ( 6.022x10^23 / 1 mol ) = 7.2107077x10^21 molecules = 7.21x10^21 molecules
Convert grams to moles using the molar mass ( g/mol ).
Use Avogadro's constant ( 6.022x10^23 ) to get the quantity of molecules from the amount of moles.
Revise answer to have the correct number of significant figures ( the smallest amount of digits in any number in the problem is the amount of significant figures your answer should have ).