Plan a marketing campaign, demand generation program, or pipeline target by working backwards from the revenue number to the volume, spend, and timing it actually requires. Use this whenever the user asks to plan a campaign, build a demand gen plan, set a marketing budget, figure out how much pipeline they need, work out required MQLs or leads, forecast whether a target is reachable, justify marketing spend, or asks "how do we hit $X". Also use it when someone proposes a campaign budget without having checked whether the math closes.
