laboratory
Quite easily because each of the 7 numerals represented a certain value. The Romans even had the equivalent of a modern day calculator to do their sums it was called an abacus device. The 7 numerical values: M=1000, D=500, C=100, L=50, X=10, V=5, I=1
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Experiment
11
tan
You can get 2, 4, 6, 8, 10, and 12, six even sums all together.
Decabbaged 10 letters. its the biggest word u can use
A whiteboard.
Hardlyever
Well, 1 is equal to 1. 9 is equal to 9. So any number from 0 to 9. I do not think this is what is meant by the question. If you mean any number with more than one digit. There is no such number. Because 11 sums to 2. 19 sums to 10. 21 sums to 3. 29 sums to 11. 111 sums 3. 119 sums to 11. The sums do not grow as fast the increase of digits.