# Of Metrics and Ages: When 0=1

June 27, 1993

Robert J. Purvis is making a big mistake if he is counting years and decades just like fingers and toes ("Metric System May Be Right for These Times," June 13). Fingers and toes are real--you can see and touch them--but years, ounces, minutes are intangible--you can't see and touch them.

Would Purvis count a newborn baby's age as "one" the day it is born? The baby tolls off a "zero year" before reaching its "one." So does a decade, and a decade begins with 0 and ends at the end of 9. That makes 10 years. Would Purvis get a bank loan with annual interest, and if he is lucky and pays the loan principal back after 364 days. . . . Well, it hasn't been a year. Does he expect the bank to say he does not owe any interest? I think not. But his loan has not reached its "one," to be counted.

Postage rates are 29 cents up to an ounce. Over an ounce, it costs for two. If a letter weighs less than an ounce, does it go for free? Oh, no. That "0" counts for 29 cents. The 0 year in a decade is that decade's first year. It ticks off 365 days before it reaches its first anniversary and earns its "one." It doesn't get a 1 before it has ticked off 365 days. If a long-distance call is charged per minute, and Purvis' call lasts short of a minute, does he avoid paying? He can try it.

Now, the clincher: Why is it called 20th Century when we are in the 1900s? Get it? From 0 to the end of 99 years made up the first century, and at the beginning of 100, the second century began. If you wait until after you "have" a century before you count it, like a toe, then Purvis wins.

TROXEY KEMPER

Los Angeles

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The first year (Year 1) of this era began at zero (on Jan. 1, 0000) and ended when Year 1 ended, on Dec. 31, 0000. At that time, we were one year old. The next day, Jan. 1, 0001, Year 2 began. People's ages are counted in the same way, though not, as was suggested, fingers and toes. Fingers and toes arrive all at once and remain so. . . .

All this is despite what intuition and conventional wisdom suggest.

HARRY M. BAUER

Sherman Oaks