A mathematician, a physicist and an engineer are given an identical problem: Prove that all odd numbers greater than 2 are prime numbers. They proceed:

- Mathematician: 3 is a prime, 5 is a prime, 7 is a prime, 9 is not a prime - counterexample - claim is false.
- Physicist: 3 is a prime, 5 is a prime, 7 is a prime, 9 is an experimental error, 11 is a prime, ...
- Engineer: 3 is a prime, 5 is a prime, 7 is a prime, 9 is a prime, 11 is a prime, ...
- Computer Scientist: 1 is a prime, 1 is a prime, 1 is a prime, 1 is a prime, ... Yes, they're all primes.

- A mathematician will be able to calculate where the shell will land
- A physicist will be able to explain how the shell gets there
- An engineer will stand there and try to catch it

- The engineer whips out his slide rule (so it's old) and shuffles it back and forth, and finally announces "3.99".
- The physicist consults his technical references, sets up the problem on his computer, and announces "it lies between 3.98 and 4.02".
- The mathematician cogitates for a while, oblivious to the rest of the world, then announces: "I don't what the answer is, but I can prove an answer exists!".
- Philosopher: "But what do you mean by 2 + 2 ?"
- Logician: "Please define 2 + 2 more precisely."
- Accountant: Closes all the doors and windows, looks around carefully then asks "What do you want the answer to be?"

- Mathematician: Pi is the number expressing the relationship between the circumference of a circle and its diameter.
- Physicist: Pi is 3.1415927plus or minus 0.000000005
- Engineer: Pi is about 3.

How they knew it was a deer:

- The physicist observed that it behaved in a deer-like manner, so it must be a deer.
- The mathematician asked the physicist what it was, thereby reducing it to a previously solved problem.
- The engineer was in the woods to hunt deer, therefore it was a deer.

- "Aha," says the engineer, "I see that Scottish sheep are black."
- "Hmm," says the physicist, "You mean that some Scottish sheep are black."
- "No," says the mathematician, "All we know is that there is at least one sheep in Scotland, and that at least one side of that one sheep is black!"