Prime Number Pop Quiz


The year 2013 has just started and while writing a check or holiday cad you may have noticed that 2013 is odd. It ends with 13 that many would rather skip. It contains all the digits in a range of 0-3 with no repetitions, however it is not a number you would call beautiful.  Definitely odd. Perhaps even prime...
Is it prime?
Nope, 2013 is divisible by 11, 3 and 61!
Dare to take a quiz about prime numbers?
If you need some muscle-buildup before the quiz, here is an article about recent prime year 2011 I wrote for The Boston Globe: 2011 is a sexy prime.

Ready for the Quiz?
Here we go:
  • 1.

1.Puzzle #1: Prime Olympics
True or false: Number of rings in the Olympic emblem is prime.  





Answer: True, there are 5 rings and 5 is a rime number.

2.



Puzzle #2: Leap Prime
True or false: Leap year cannot be a prime number year.  






Answer: true, leap year numbers are divisible by 4.


3.

Puzzle #3: Infiltrator
Which of the following four numbers is not a prime: 1, 37, 911, 991. 






Answer: 1 is not prime because prime should have two different divisors: 1 and itself. However, long time ago 1 was considered to be a prime.

4.

Puzzle #4: What are primes?
Which one of the following is a correct definition of a prime number:

  1. Odd number ending with 1, 3, 5, or 7. 
  2. Any number present in the multiplication table. Multiplication table is a “base” of all the numbers. 
  3. Number that can be divided by only two distinct divisors. 
  4. Number that looks the same left-to-right and right-to-left. 






Answer: #3.

5.

Puzzle #5: Prime Flowers.
True or false: Number of petals in any flower is always prime.  








Answer: false. There are 4 petal flowers, 4 is not a prime.

6.

Puzzle #6: Even Primes
True or false: No even number is prime because all even numbers are divisible by 2 in addition to divisors of 1 and itself.  









Answer: this is false because 2 is a prime number. The only even prime. It is divisible by 1 and 2.
7.



Puzzle #7: Math Magic
True or False: This trick can only be done in the prime year such as 2011:  Take the age you were in 2011, add the last two digits of the year you were born and get a number that ends with 11 or 111. 










Answer: This trick will work for any year that ends with 11 such as 1911. And 1911 is not prime: 1911 = 3 x 7 x 7 x 13  Therefore the magic statement is false.
In general, if you add your age to the year you are born you will always get current year. So in 2011 it will end with 11, as well as in 1911 and 3311.

8.



Puzzle #8: Prime Senate.
Number of Democrats in the US Senate is a prime number as well as the number of Republicans in the US Senate.  








Answer: This is true.  There are 47 Democrats and 53 Republicans currently in US Senate.


9.Puzzle #9: Prime 108
True or false:  Famous “Prime 108” restaurant in Nashville, TN located in the Union Station is named after prime number 108 that is the number of entries on their menu. 










Answer: false. 108 is not a prime number (108=54x2). The restaurant is named for a Bully 108, the first steam engine to chug through Union Station, and "prime" alludes to the high-quality ingredients used to compose the dishes.
10.




Puzzle #10 A Special Year.
True or false: Current year is rather special. It is prime in the Gregorian calendar – year 2013; prime in the Islamic calendar – year 1434. And prime in the Hebrew calendar – 5773. 








Answer: false. 2013, 5773 and 1434 are not prime numbers.

This quiz was created by TheMathMom for the Boston Globe in 2011. Link.

9 comments:

  1. Any two odd numbers when subtracted, leaves an even number. For example 33 - 27 (neither of which is primes leaves 6.

    Statement: it is never possible for two primes when subtracted to leave a prime number. True or false?

    There is such a thing as 3 consecutive prime numbers? True or False

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