One cannot ignore the numbers if one wishes to understand this world better. There is no area where we will not find the numbers. Be it mathematics, science, economy, geography, physics or even history, we need the help of numbers to know their applications and importance in our life. Scientists can calculate the distance of moon from the earth with the help of numbers, historians take the help of numbers to estimate the age of any civilization, geologists can predict the amount of water in the air with these numbers and there are so many other philosophies where we need these numbers. So is it not worth spending and taking out some time in knowing at least the basic properties of these numbers? Is it not important to at least know their contributions in our daily life? After all, they decide our mobile numbers, they tell us where we stand in our exams, they tell us the right measure of clothes we should wear. And here, they will decide your performance in the entrance examination you are preparing for.
Topics covered in this chapter are
1. Real numbers , Whole number , Rational number , Irrational numbers , Integers , Natural numbers, LCM and HCM
2. Divisibility Rules by : Numbers 2, 3 ,4,5,6,7,9,11,13 and 17
3. How LCM and HCF are to be interpreted