NUMBER STORIES
Tens
UnitsTensUnitsTensUnits
First StepSecond StepThird Step
HOW CAIUS ADDED WITH PEBBLES
If Caius wished to add XXII and CXXXVIIII, he first placed 2 pebbles on the units’ line, as shown in the First Step. He then placed 9 more, as shown in the Second Step. He then took away 10 of these pebbles, and added one pebble to the tens’ line, as shown in the Third Step. The rest of the work is shown on page 49
By placing the pebbles on the lines for units, tens, and so on, he could add quite rapidly.
Of course he could not add as rapidly as we do, but no one could work very quickly with
numbers in those days, and Caius did as well as anyone else. People did not have much
work to do with numbers, and they were not in as great a hurry as we are.
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