1 . Which one of the following is the next number in the series : 7, 7, 14, 42, 168-----?

• A. 336
• B. 504
• C. 672
• D. 840
• D. None of these

Answer: Option D

Explanation:

7  ×  1  =  7;7  ×  2  =  14; 14  ×  3  =  42; 42  ×  4  =  168; 168  ×  5  =  840