Subtracting

Once you go ahead and start, even the tiresome work of adding and subtracting figures is interesting in its way.

"It is one thing to write as a poet and another to write as a historian: the poet can recount or sing about things not as they were, but as they should have been, and the historian must write about them not as they should have been, but as they were, without adding or subtracting anything from the truth."

Subtracting an odd number from an odd number will result in an even number.

[…] she is confronted with the menacing reality of her incompetence. Which is not to say she can't do the addings and subtractings.