prime number

[datdat]

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it's from kap flashcard but no answers..

what is the greatest prime number less than 37..

what is the systematic way to solve this?

 

[jay47]

it's from kap flashcard but no answers..

what is the greatest prime number less than 37..

what is the systematic way to solve this?

Just go down, and remember the largest EVEN prime number is 2.

37---35 (nope, /5)----33(nope, /11)----31 (YES!) that's its.

Remember that there are no even prime numbers aside from 2, and all numbers that end with a 5 (except 5) are not prime, that leaves only 4 values for every 10 numbers. Should be able to do it pretty fast...

This link is useful for seeing the first bunch of prime numbers....http://www.math.utah.edu/~pa/math/primelist.html

Notice that all of the numbers will end in 1, 3, 7, 9 after prime number 5.

 

[datdat]

Just go down, and remember the largest EVEN prime number is 2.

37---35 (nope, /5)----33(nope, /11)----31 (YES!) that's its.

Remember that there are no even prime numbers aside from 2, and all numbers that end with a 5 (except 5) are not prime, that leaves only 4 values for every 10 numbers. Should be able to do it pretty fast...

This link is useful for seeing the first bunch of prime numbers....http://www.math.utah.edu/~pa/math/primelist.html

Notice that all of the numbers will end in 1, 3, 7, 9 after prime number 5.

thank a million!!!