If anyone can tell me if there is a way to the following, I'd love them forever

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When you copy and paste a formula Excel adjust for the position of where you are pasting it.
For a simple example, if I copied the formula "=A1 + 2" from cell B1 and pasted it to B2 the formula in B2 would adjust to "=B1 + 2".
What I would like to achieve is keeping part of the formula fixed on a specific cell no matter where I paste it. Basically, using the example above I'd like paste it into B2, but still have it read the value in A1 instead of B1.
Is this possible? If so, how?
Thanks