Easy
7, 11, 13, 17, 19, 23, ........?........, 29
Explanation
Explanation
Check the gap between consecutive numbers: 11-7=4, 13-11=2, 17-13=4, 19-17=2, 23-19=4. The gaps alternate between +4 and +2. Following this pattern, the next gap after 23 should be +2, giving 23+2 = 25. Check it works forward too: 25 to 29 is a jump of +4, which fits the alternating pattern perfectly. So the missing number is 25, option (2).
PRO TIP
Re-check your working by substituting the answer back into the original question.