I have a column of random numbers that all begin with 'B*****' where the stars are numbers. I need a formula to add 1 (+1) to the cell on the right of the number and take away 1 (-1) to the left of the number.

E.g. If B00001 is in the centre

B000002 should be on the right B000000 should be on the left of it

How do I achieve this? Tried to select a couple of cells and dragging them to the right and 'down' but it will just copy and not add!