you can tender any no. of shares in buyback from 1 share upto any number, which you are holding till record date. for 1 share tender, it will be accepted in buyback. for 3 share tender, 2 might be accepted mostly.
How come now it is 1.21 times over subscribed? I think BSE must have made some mistake in typing. Total 241 cr received, still 159 cr available. So apply.