document.write( "Question 344426: How many prime numbers less than 200 are 1 more than the square of an integer? \n" ); document.write( "

Algebra.Com's Answer #246391 by vleith(2983) $\"\"$ $\"About$

You can put this solution on YOUR website!
Trial and error. Easiest to do squares and then test
\n" ); document.write( "1^2 = 1 1+1 = 2 2 is prime
\n" ); document.write( "2^2 = 4 4+1 = 5 5 is prime
\n" ); document.write( "3^2 = 9 9+1=10 --> not prime
\n" ); document.write( "4^2 = 16 16+1 = 17 17 is prime
\n" ); document.write( "Just keep doing that.
\n" ); document.write( "After a few odd numbers, you'll see that odd squared +1 is even, which cannot be prime.
\n" ); document.write( "14*14 is just below 200, so you only need to do even integers from 6 thru 14 and test them
\n" ); document.write( "If you don't know what numbers are prime, look here
\n" ); document.write( "http://www.math.utah.edu/~pa/math/primelist.html\r
\n" ); document.write( "\n" ); document.write( "You can do it from here \n" ); document.write( "

\n" );