Mathematics Dictionary Dr. K. G. Shih

Week Day of Given Date

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Question and Answer

Q01 Q1. Find the week day of December 7 of 1941 Q02 Q2. Find day of week of 25 December of 1985 Q03 Q3. Find day of week of 7 July of 1937 Q04 Q4. Find day of week of 25 December of 2056. Q05 Q5. What is leap year ? Q06 Q6. How to use the index table for March 1 of 1800 to Feburary 28 of 1900 ? Q07 Q08 Q09 Q10

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Answers

Q1 : Find week day of December 7 of 1941 ? Week Day Index 1. Week day table can be used for March 1, 1900 to Feburay 28, 2100 2. Week day table from 1956 to 1983 at left column and 1984 to 2011 at right 3. Find index for year 1941 a. 1956 - 28 = 1928 b. Left column years from 1928 to 1957 c. Hence the corresponding row for 1941 + 28 = 1969 4. Month index for December of 1969 column is 0 5. x = day 7 + month index = 7 + 0 = 7 6. x/7 = 7/7 = 1 and remainder is 0 7. Since remainder is zero, hence it is Sunday 8. This is the day when Japan invaded Pearl Harbour Go to Begin Q2 : Find day of week of 25 December of 1985 Week Day Index * Index for December of 1985 is 5. * Day 25 + Index number = 25 + 5 = 30. * 30 divide by 7 = 4 and remainer 2. * Since remainder is 2, hence it was Tuesday. Go to Begin Q3. Find day of week of 7 July of 1937 Week Day Index * 1937 is not in the index table. What should we do ? * 1937 + 28 = 1965. The year is also not in the Table. * 1965 + 28 = 1993. The year 1993 is in table. * Use index of 1993 for year 1937. * For July of 1993 the index number is 3 * x = day 7 + index 3 = 10>br> * x/7 = 10/7 = 1 ..... 3 * Since remainder is 3 Hence it is Wednesday * This is the day when Japan invaded China Go to Begin Q4. Find day of week of 25 December of 2056. * Year 2056 is not in the table. What should we do ? * 2056 - 28 = 2028. The year is also not in the Table. * 2028 - 28 = 2000. The year 2000 is in table. * Use index of 2000 for year 2056. * Index of Decomberof 2056 is same as index December of 2000. * Hence index for December of 2056 is 4 * x = day 25 + index 4 = 29 * x/7 = 29/7 = 4 ..... 1 * Hence it is monday Go to Begin Q5.: What is leap year ? * In leap year, Feburary has 29 days. * Year is a leap year if it is divisible by 4. * Centenium year is a leap year if it is divisible by 400. * The index table is taken from p135 of Computer Mathematics. * Why add ... in table ? Because Html only give one space. [Example] Year 1900 A.D. is not leap year. Why ? * Year 1900 is divisible by 4. * Year 1900 is not divisible by 400. Go to Begin Q6. How to use the index table for March 1 of 1800 to Feburary 28 of 1900 ? Find week day of Feburary 28 of 1900 1900 + 28 = 1928 1928 + 28 = 1956 Hence we use the index column of 1956 For Feburary the index is 2 Hence (2 + 28)/7 = 4 ..... 2 Hence Feburary 28 was Tuesday Find week day of March 1 of 1900 1900 + 28 = 1928 1928 + 28 = 1956 Hence we use the index column of 1956 For March the index is 3 Hence (3 + 1)/7 = 0 ..... 4 Hence March 1 was Thursday Since 1900 was not leap year, it had no Feburary 29, Hence Feburay 28 of 1900 should be wednesday. Index for March 1 of 1800 to Feburary 28 of 1900 The index for each month should add 1 The index for Feburay of 1900 is 2 + 1 = 3 Hence (3 + 28)/7 = 4 .... 3 Hence it is wednesday Go to Begin Q7 : Go to Begin Q8. New question Go to Begin Q9. New question Go to Begin Q10 New question Go to Begin

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