How many prime numbers between 0 to 50?  Choose the correct choice:
A) 11 B) 13 C) 14 D) 15 E) 16
primes are of the form 6n+1 or 6n-1   Put n=0   6n+1=6*0+1= 
<gadget id="calculator">6*0+1</gadget>
<output>1</output>
1 where 1 is not prime   for n=1   6n+1=6*1+1= 
<gadget id="calculator">6*1+1</gadget>
<output>7</output>
7 and 6n-1= 6*1-1= 
<gadget id="calculator">6*1-1</gadget>
<output>5</output>
5   for n=2   6n-1= 11 and 6n+1=13   for n=3 , ==&gt; 19 and 17   for n = 4 ==&gt; 23   for n =5 ==&gt; 29 and 31   for n = 6 ==&gt; 37   for n=7 ==&gt; 41 and 43   for n = 8 ==&gt; 47   therefore total number of prime numbers = 13 + 2(since 2 and 3 are prime numbers) =15   Ans - 15
<result>D</result>
How many prime numbers between 0 to 50?