Can anyone out there explain to me like a five year old boy how the formulae for calculating the IODINE NUMBER and CHLORINE NUBER of fats were derived?

The iodine number is more measured than calculated. It is found by adding iodine to the fat. The iodine will open and add to the double bonds in an unsaturated fat. An equivalent of oleic acid with one double bond, will add 2 equilivents of iodine. Linoleic with 2 double bonds will add 4 equilivents. A pair of conjugated double bonds will only add 2 instead of 4. Iodine number is reported as grams per 1000 grams. Possibly grams of potassium hydroxide instead of iodine. Been about 30 years since I have looked at this stuff. If you need help with equivalents, you should be able to find it in a chemistry text book.