TABLES FOR COMPUTING DECIMAL FRACTIONS OF A YEAR
Donald McVarish · Child Development · 1962
A research worker who concerns himself with exact proportions of a year between, for example, a subject's birthday and the day that subject was measured for mental or physical growth must usually consult both his calendar and his calculator in order to be precise. The Pearl and Miner table (i) is helpful as an alternative procedure, but it does not always yield greater than two-place accuracy. It has been the writer's experience that three-place accuracy is often necessary. The accompanying tables are designed to give exact decimal equivalents of a year to four places between any two dates. In addition to the greater accuracy achieved by these tables, there is another attraction for those who dislike adding and subtracting fractions. All necessary arithmetic is accomplished in Table I with whole numbers-days-and the results are referred to Table 2 for conversion to fractional equivalents of a year. Table I presents each day of a 365-day year in terms of its number within the year (elapsed time since December 31) and in terms of the number of days remaining in the year after that day. To find the number of days elapsed between two dates within a calendar year, it is only necessary to subtract the number of the earlier day from the number of the later. For example, elapsed time between May i6th and August 23rd is found by subtracting 136 from 235, i.e., 99 days. To find elapsed time between days in different years, such as July 15, 1958 and February io, 1961, it is necessary to find the number of days remaining in the year after the first date and add to that number the number of days since December 31st to the second date, allowing of course for any complete years between the two dates. In this example, 169 days remained in 1958 after July i5th; two years and 41 days more had elapsed to the Ioth of February, 1961. So between the first date and the second a total of two years and 21o days had elapsed.