If the contents of exchangeable ions (cmol kg^-1) determined in soil are Na⁺ = 5, K⁺ = 5, Ca²⁺ = 10, Mg²⁺ = 2, H⁺ = 1, Al⁺³ = 1, Cl^- = 1.6 and HCO^-₃ =0.4, the CEC of soil is

CEC is cation exchange capacity is a measure of the soil’s ability to hold positively charged ions.
If the contents of exchangeable ions (cmol kg^-1) determined in soil are
Na⁺ = 5
K⁺ = 5
Ca²⁺ = 10
Mg²⁺ = 2
H⁺ = 1
Al⁺³ = 1
Cl^- = 1.6
HCO^-₃ = 0.4
Summing up all the values of positive ions, we get the value of CEC of soil i.e. 24 cmol (P⁺) kg^-1