Number series – constant decrement: 72, 63, 54, 45, ? Identify the next term when each step decreases by the same amount.

Introduction / Context:Here the series decreases linearly. Constant negative first differences are as common as constant positive ones and should be checked immediately.

Given Data / Assumptions:

• 72, 63, 54, 45, ?
• Uniform decrement suspected.

Concept / Approach:Compute a couple of differences: if they match, apply the same difference again to get the next term.

Step-by-Step Solution:

Verification / Alternative check:Working backward (36 + 9 = 45) supports the same constant step.

Why Other Options Are Wrong:

Common Pitfalls:Confusing with ratio-based decreases; here the unit drop is fixed.

Final Answer:36