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On a "prime date," both the month and the day are prime numbers. For example, Feb. 7 or 2/7 is a prime date. How many prime dates occurred in 2020?

 Jun 5, 2021
 #1
avatar+179 
+1

Because 1 is not prime, there are 0 prime dates in January.  

 

2 is prime, so the prime dates in February are 2/2, 2/3, 2/5, 2/7, 2/11, 2/13, 2/17, 2/19, and 2/23 for a total of 8

 

3 is prime, so there are 10 prime dates in March.  

 

4 is not prime, 0 April Prime dates

 

5 is prime, 10 prime dates in May

 

6 is not prime, 0 June prime dates

 

7 is prime, 10 July prime dates

 

8 is not prime, 0 August prime Dates

 

9 is not prime, 0 September prime dates

 

10 is not prime, 0 October prime dates

 

11 is prime, 9 November prime dates

 

12 is not prime, 0 December prime dates.  

 

Together, there are 1+8+10+0+10+0+10+0+0+0+9+0 = 48 prime dates in 2020, 49 on a leap year (2/29 on Febuary)

 Jun 5, 2021
 #2
avatar+71 
+5

im too lazy to write it all down but we eliminate January, April, June, August, September, October, and December since they arent prime.

2020 was a leap year so we count February 29

if we add all the dates together, we get 53

 Jun 5, 2021
edited by FeedMePi  Jun 5, 2021

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