When I find alternative approaches to answer product case questions, I share them. While I have my preferred methodologies, I am always willing to share other approaches, in the event they help my clients.

In this article, Sri Gari (an ex-Googler) shares his approach to estimation questions. He even includes a video.

The Methodology

1. Clarify. Make sure you understand the core components of the question

2. Approach. Mathematical approaches to the problem

3. Validate. Sanity Check your answer.

Mathematical Approach

• Mathematical formula: Equation to be used for computing the answer.

• Breakdown: Break into multiple variables and compute them separately.

• Substitution: Plug in numbers into the formula.

• Calculate: Do the math to compute the final answer.

Estimation Question Types

• Sizing. Think market size or amount of storage needed.

• Volume. Number of X in Y. Think number of restaurants in a city.

Examples Provided

• What is the market size of the refrigeration industry?

• How many kayaks do you need for your startup in Seattle?

Tips & Tricks

This includes many of the same tips & tricks I share in my methodology as well.

• Clarify anything ambiguous. (See my advice on diagraming prompts, it applies.)

• More than one solution.

• Round numbers.

• Keep track of units.

• Use symbols.

• Double check: Always sanity check