Molar mass of Ca(OCl)2\mathrm{Ca(OCl)_2}Ca(OCl)2 = 40 + (16 + 35.5)x2 = 143
% by mass of calcium in the compound = mass of calcuimmolar mass of compound\;\frac{\text{mass\;\;of\;\;calcuim}}{\text{molar\;\;mass\;\;of\;\;compound}}molarmassofcompoundmassofcalcuim x 100%
% calcium = 40143×100\;\frac{40}{143} \times 10014340×100
= 27.98% = 28%
