As an engineer, I have a preference for the number 3. This number is so incredibly meaningful and versatile.

Think about this:

There are 3 dimensions in space that make up the component vectors of any vector in that space.

One wants at least 3 quotes for the cost of a product or service in order to have the possibility of getting a sense of a reasonable price.

3 is a great factor of safety. Design anything, then multiply the answer by 3 just to be sure.

And since 3 is a great number for having as the number of reasons that 3 is a great number, then I hesitate to mention any more of them. Suffice it to say, 3 is an engineering number.