In the following question, select the missing number from the given decreasing series: 47, 44, 40, 37, ?, 30.

Introduction / Context:
This question presents a decreasing number series where one term is missing. The purpose is to identify the pattern of subtraction that connects each term and then find the missing number. Such problems are common in verbal reasoning sections because they require quick observation rather than heavy calculation.

Given Data / Assumptions:

- The given series is 47, 44, 40, 37, ?, 30.- The numbers are decreasing overall.- Exactly one term between 37 and 30 is missing.

Concept / Approach:
For decreasing sequences, we usually look at how much is being subtracted each time. If the decreases are not constant, they may follow an alternating pattern such as subtracting two different fixed numbers in turn. Once we recognise the cycle of subtractions, we can extend it to determine the missing term.

Step-by-Step Solution:
Step 1: Find the difference between the second and first terms: 47 - 44 = 3.Step 2: Find the difference between the third and second terms: 44 - 40 = 4.Step 3: Find the difference between the fourth and third terms: 40 - 37 = 3.Step 4: So the pattern in differences is -3, -4, -3, and it is natural to expect the next difference to be -4 again, continuing the alternation of subtracting 3 and 4.Step 5: Subtract 4 from 37 to get the missing term: 37 - 4 = 33.Step 6: Finally, check the last difference: 33 - 30 = 3, which returns to subtracting 3.

Verification / Alternative check:
With the missing value inserted, the series becomes 47, 44, 40, 37, 33, 30. Now check all differences: 47 - 44 = 3, 44 - 40 = 4, 40 - 37 = 3, 37 - 33 = 4, 33 - 30 = 3. The pattern is clearly subtract 3, subtract 4, subtract 3, subtract 4, subtract 3, confirming that 33 is correct.

Why Other Options Are Wrong:
If we choose 32, the differences 40 - 37 = 3, 37 - 32 = 5 and 32 - 30 = 2 do not follow any simple alternating pattern. For 34, the gaps become 3, 4, 3, 3 and 4, which again breaks the clear alternating structure. Option 31 also fails to produce a neat repeat of the subtract 3, subtract 4 pattern. Therefore these values are inconsistent with the rule of the series.

Common Pitfalls:
Students sometimes try to fit a complicated formula or see prime numbers without first checking basic differences. Another mistake is to treat the decreasing series as if it had a single constant difference, when in fact an alternating pattern is present. Always list all the differences to see whether they themselves form a simple sequence.

Final Answer:
The missing number in the series is 33.