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If you need to check a column of numbers, forget the adding machine unless you’re a touch typist.

Absolute accuracy is usually not important. You could just add the dollars and ignore the cents in most cases. An even quicker way of checking is to round the dollar amounts.

Supposing you had the following five figures to add up: $350, $275, $176, $47 and $521. My adding machine makes that $1369 in total. Now try rounding the figures as follows: $400, $300, $200, $0 and $500. You will see this makes a total of $1400 and it is very easy to add it up in your head. The figure of $350 is exactly halfway between $400 and $300, so we rounded up to 400. $275 becomes $300 because this is the nearest round figure and $47 becomes nil because it’s below the halfway point between $100 and $0.

If absolute accuracy doesn’t matter then $1400 is near enough and you know there hasn’t been a major mistake.

If you’re checking a column of figures with someone else and they are hand written, make sure the person calling the hand-written figures is not the same person as the one who added them up in the first place. The second person might see a hand-written figure as being different from the way the first person read it.