sir, i find a little difficult .that is: i get confused and i dont know when & where to apply HCF and LCM? can u please help me sir?
You may see the solutions of related problems, and remember for so and so situation, it's HCF and LCM problem. Try to gather various different types of problems that require HCF and LCM. Practice solving similar problems and then you might be able to judge as to what problems require HCF and LCM.
For example, the problem that 3 people start running around a circle with different speeds, hence they'll take different times to complete the circle. To find when they'll meet at the same point again, is a HCF problem.
Show that every positive even integer is of the form2q and every positive odd
integer is of the form 2q +1where q is some integer.