what is calgon's method plzz explain mee toommo r my xamzzz

Sodium hexa meta phosphate is called calgon. Its molecular formula is (NaPO₃)₆ or Na₆P₆O₁₈. It is used as ion exchange for softening of water. When Calgon react with hard water, it exchange calcium and magnesium ion present in the water with sodium. In this way water become free from hardness occurring due to Calcium and magnesium

  Na₂[Na₄(PO₃)₆] +  2Ca²⁺  →  Na₂[Ca₂(PO₃)₆]  + 4Na⁺