Friday Be An Unlucky Day
Detective Riddles
One day a kid challenges Riddle master Gogo to solve a riddle. The child claimed that he was smarter than Gogo.
As soon as Gogo accepted the challenge, the child asked him, "Many people would think Friday the 13th will be an unlucky day. Is it possible that there is no Friday on 13th through the whole year? How many Fridays at 13th can we have in a year at most? Can you calculate it out?" Gogo solved the riddle and proved himself smarter. How did he do it, can you calculate ?
Gogo thought to himself," I can calculate out how many days there will be for the 13th on each month if i count from the beginning of the year (January 1). Then i can divide total days by 7 to get the remainders. I will also need to consider the leap year. Through the whole year i had all kinds of remainders, from 0 to 6. The minimum of occurrence for all the unique remainders was 1. It means that there is at least one Friday on 13th. In a regular year, the best chance you can get 3 Fridays on 13th, which are in February, March and December because the remainders of these 3 months are 2. In a leap year, the best chance you also can get 3 Fridays on 13th, which are in January, April and July because the remainders of these 3 months are 6. Gogo thought to himself," I can calculate out how many days there will be for the 13th on each month if i count from the beginning of the year (January 1). Then i can divide total days by 7 to get the remainders. I will also need to consider the leap year. Through the whole year i had all kinds of remainders, from 0 to 6. The minimum of occurrence for all the unique remainders was 1. It means that there is at least one Friday on 13th. In a regular year, the best chance you can get 3 Fridays on 13th, which are in February, March and December because the remainders of these 3 months are 2. In a leap year, the best chance you also can get 3 Fridays on 13th, which are in January, April and July because the remainders of these 3 months are 6.
-
Gogo thought to himself," I can calculate out how many days there will be for the 13th on each month if i count from the beginning of the year (January 1). Then i can divide total days by 7 to get the remainders. I will also need to consider the leap year. Through the whole year i had all kinds of remainders, from 0 to 6. The minimum of occurrence for all the unique remainders was 1. It means that there is at least one Friday on 13th. In a regular year, the best chance you can get 3 Fridays on 13th, which are in February, March and December because the remainders of these 3 months are 2. In a leap year, the best chance you also can get 3 Fridays on 13th, which are in January, April and July because the remainders of these 3 months are 6.