Each of the different arrangements which can be made by taking some or all given objects is called Permutation. Permutation of objects means arrangement of the objects in which order of things is taken in account.
Suppose one book each of Mathematics, English and Science are to be arranged on a book shelf, then following six arrangements are possible.
They are
MES → Arrangement 1
MSE → Arrangement 2
SME → Arrangement 3
SEM → Arrangement 4
EMS → Arrangement 5
ESM → Arrangement 6
Here, M stand for Mathematics book, E stand for English book and S stand for Science book.
You can now observe that changing the order of a book will result to a new arrangement.
Example:
Six arrangements can be made with three books taken two at a time.
MS, SM, ME, EM, ES and SE.
Each of the different groups of selections which can be taking some or all the given objects at a time is called Combination. Combination is an arrangement of objects in which the order of objects does not matter.
Example:
The groups that can be made with three different books taking two at a time is
MS, SE and EM.
