Find the missing term in the series given below. 12, 13, 18, 19, 24, 25?
(a) 27
(b) 30
(c) 29
(d) 26

Hint: For this problem, we will understand the series by observation in the problem and then solve for the required number.

Complete step-by-step answer:
Mathematics is related to all the phenomena occurring in the world. In mathematics, various problems related to series are based on a certain pattern which is recurring. By observing this pattern, we can easily follow the series and predict the number which will satisfy the given series. In our problem, we are given a similar series of numbers 12, 13, 18, 19, 24, 25.
We try to find out some relationship between the numbers. On observing the numbers carefully, we notice that the difference between the first and third term is 6. Similarly, the difference between the second and fourth term is 6. This pattern is observed for further terms. Now we can easily predict the next number.
Let, the number be x.
$\begin{align}
  & \therefore x-24=6 \\
 & x=30 \\
\end{align}$
The next number in the series is 30.
Therefore, option (b) is correct.

Note: The key step for solving this problem is the knowledge of series and basic skills of observation. By observing the pattern, we can easily predict the next element in the series. This knowledge is useful for solving complex problems.