My english incharge teacher told  me and my class a formula for solving the direct and indirect speech that is "SON divided by 123 but i could not understand it if anybody knows this answer plz tell me fast.

Various rules to convert direct into reported speech are:

• A simple present becomes a simple past;

• A present continous becomes a past continous;

• A present perfect becomes a past perfect.

• The 'shall' of the Future tense is changed into 'should'.

• The 'will' of the Future tense is changed into 'would' or 'should'.

• The pronouns of the Direct speech are changed wherever necessary, so that their relations with the reporter and his hearer, rather than with the original speaker, are indicated.

• Words expressing nearness in time or place are generally changed into words expressing distance. For instance, now becomes then, ago becomes before, tomorrow becomes the nest day and last night becomes the night before.

• The tenses may not change if the statement is still relevant or if it is a universal truth.

As far as the rule mentioned by you is concerned, it is not a universal one. It might have been formed for the easier comprehension of students. For further doubts, you are most welcome with your queries, suggestions and feedback.