Sol. 100years have = 5 odd days ∴ Last days of Ist century is Friday
200years have = 10 odd days ∴ Last day of IIst century is Wednesday
= 3 odd days
300years have = 15 odd days ∴ Last day of IIIrd century is Monday
= 01 odd day
400years have = (5 × 4 + 1) Last day of 4th century is Sunday
= 21 odd days
= 0 odd days
Since the order keeps on cycling, we see that the lat day of the century cannot be Tuesday, Thursday or Saturday.
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Tables: For calculating odd days |
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| Month |
Jan |
Feb |
March |
April |
May |
June |
July |
Aug |
Sep |
Oct |
Nov |
Dec |
| Odd days |
3 |
0/1 ord./Leap yr |
3 |
2 |
3 |
2 |
3 |
3 |
2 |
3 |
2 |
3 |
| Months of years |
Ist three months 1 Jan to 31 March |
IInd Three months 1 Apr to 30 Jun |
IIIrd three months 1 July to 30 Sep. |
Ivth (last) three months |
Total year 1 Jan to 31 Dec. |
| Total days |
90 / 91 ord / leap |
91 |
92 |
92 |
365/366 ord./leap |
| Odd days |
6 / 0 ord./leap |
0 odd day |
1 odd day |
1 odd day |
1 / 2 odd days |
