Mathematical models could be helpful in assisting the Indian government's new initiative of issuing biometric cards to its citizens. This note examines the role of mathematical models in estimating the missing, non-enumerated population numbers, and in estimating the number of cards required by age, gender and regions annually in India. The link between the National Population Register and biometric cards is also highlighted. There are other scientific issues, such as electronic security, data storage management and identity verification, which we do not model in this paper, though we address the role they play in successful implementation.