How many times has the Indian Rupee been devalued?

The Indian Rupee was devalued in three instances. The Indian rupee was devalued for the first time in 1949, later it was devalued in 1966 and finally the Indian rupee was devalued in 1991. In 1991, the Indian rupee was devalued in two steps, first on 1st July and again on 3rd July. You can read about the Balance of Payment Crisis, 1991 – Causes and Measures to Control it in the given link.

Further readings:

1. Forex Reserves – Meaning, Importance, Advantages (Notes for UPSC IAS exam)
2. New Economic Policy of 1991 – Objectives, Liberalisation, Privatisation, Globalisation