We will teach this concept in the form of a story. Mr. T and Mr. O are two brothers. Mr. T is an  elder brother and Mr. O is  a younger brother. Working capacity of Mr. T is more. Mr. O’s capacity is  very less. Mr. O cannot carry anything more than 9. If he is given more  than nine , he will give some to Mr. T in bundles of tens.(i.e. 1 tens, 2 tens, 3 tens and so on)

                        e.g.                      T                  O

                                                    1

    3                   7

+  4                    3

     8                  0

  Mr. O is given total 10 books. So he will give 1 ten to Mr. T , now Mr. T has 3,4 and 1 book  which is 8. The sum of 37 and 43 is 80.