the formula equation is as follows
Ca(OH)2(aq) + 2 HClO3(aq) -----> Ca(CIO3)2 + 2H2O
from equation above; 1 mole of Ca(OH)2 reacted with 2 moles of HClO3 to produce 1 mole of Ca(CIO3)2 and 2 moles of H2O
there are total of three moles in both the reactant side and the product side