What is the formula to calculate cobalt? The result i've got for titration are 3.9,4 and 3.9cm3.

Determination of Cobalt Transfer accurately 0.1 grams of Hexammine Cobalt(III) chloride into a beaker and add 20 cm3 of 2H sodium hydroxide solution. Boil the solution for five minutes. Cool the solution and add 1 gram of potassium iodide. Acidify with concentrated hydrochloric acid. When all the black Cobalt (III) Oxide has dissolved, titrated with 0.1 M sodium thiosulphate using starch as an indicator. At the end point a pink colour is observed. Calculate the nercentage cobalt in the product