The Power of Iterative Delivery and Adaptive Planning

As a coach, it is nice to have some simple ways to show people the power of Agile methods. This quick little exercise is an excellent way to demonstrate the weakness of the waterfall approach to working with up-front requirements analysis versus the power of the agile iterative/adaptive approach. UPDATED 20051213!

Find the Number

Work in pairs with someone you don’t know. One person will choose a number at random between 0 and 1000. The other will try to figure out the number chosen. You have sixty seconds to communicate the number but…


1. Write down the number so the other person can’t see it.
2. Come up with clues about the number. You cannot use any math either explicitly or implicitly in your clues. E.g. if the number is “256” here is a good clue: “the first and second digits are rotationally symetrical on an LED display”, and here is a disallowed clue: “it is an even number” (uses a mathematical feature).
3. As you figure out clues, tell them to the other person.
4. The person trying to determine the number cannot ask questions.
5. Before the sixty seconds are up, the person must state a number they think is correct (and the other person must tell them if they are correct). Only one “guess” is allowed.


1. Switch roles with your partner.
2. Write down the number so the other person can’t see it.
3. The person trying to find the number guesses a number at random.
4. The person who knows the number tells the other person if the guess is low, high or correct.
5. Repeat steps 3. and 4. every six seconds.


1. How was the first part of the exercise like the waterfall method? Was it successful/how close did you get?

2. How was the second part of the exercise like the iterative/adaptive method? Was it successful/how close did you get?

3. What other interesting things did you notice about this exercise?

Acknowledgements: the second part of this simulation exercise comes from a discussion with Jim York of CCpace.

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