What is the mass in grams of 4.8x10^24 atoms of strontium

I don't know if you already know about the mole hold but basically you must convert into moles to get to another thing there are no shortcuts.

First you must divide 4.8x10^24 by avagadros number (6.02x10^23) doing this will convert 4.8x10^24 atoms into moles

Next take the moles and multiply it by the molar mass of strontium to get the mass in grams

(4.8x10^24) / (6.02x10^23) = 7.973421927moles

Multiply the number of mole by the molar mass of strontium (88g/mol)

7.973421927x88=701.67g