The sum of the non-prime numbers between 10 and 20, non-inclusive, is Choose the correct choice from the following answers.
A) 60 B) 75 C) 90 D) 105 E) 120
sum of consecutive integers from 11 to 19, inclusive ====&gt; (A1 + An)/2 * # of terms = (11 + 19)/2 * 9 = 15 *9= 
<gadget id="calculator">15 *9</gadget>
<output>135</output>
135   sum of non-prime numbers b/w 10 and 20, non inclusive===&gt; 135 - 60 (i.e., 11 + 13 + 17 + 19, being the prime #s in the range) = 75   Answer: 75
<result>B</result>
The sum of the non-prime numbers between 10 and 20, non-inclusive, is