How many Black Fridays the 13 are there in a year?
Maximum number of Black Fridays in a year is 3!!!
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- Elaine
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We basically use the same kind of table to solve the problem. However, I feel that the number can be simplified a little bit. For example, from January to Feb, there are 31 days(=28 + 3). Because 28=4*7, it will not change the day in a week. It is basically the 3 extra days that have influence. Therefore, we can simplify the calculation by using 3 instead of 31. The same rule applies to the rest of the month. Good job over all! Very clearly written paper.
ReplyDeleteIt took me a while to understand your method, namely the table on the left, but now I do understand it. Your method is a more numerically than mine. That might be an advantage because then you can mechanize and anticipate results in the distant future.
ReplyDeleteIthink you missed to say what is the least possible number of Black Fridays in a year.
Good job.
It was great to have a base case and i really like the table idea. The table was a bit hard to understand though, so maybe explain it on the right hand side, but once you get it it's great. It was good to mention to that same days fall on multiples of 7 days and that's how you found the number of black fridays. Go Elaine!
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