Hi Nisha.

For finding out the group number of an element in the periodic table, you need to first write its electronic configuration. Then, you need to check the number of electrons in the outermost shell of the element. For s block, the Group Number is equal to the number of electrons in the outermost shell. For p block, Group number is equal to the number of electrons in the outermost shell + 10. For d block, Group number is equal to the no. of electrons in the outermost shell + no. of electrons in the penultimate shell.