If I were to build a new house, what tools should I use?

I am a noobie on a budget, and have been researching calculators. From what I can glean from old texts and experienced engineers, a slide rule is a very handy tool for solving complex mathematical calculations. From what I can tell, in the hands of a knowledgeable, competent engineer, a slide rule can get the job done in most applications. On the other hand, a calculator is not all that expensive and is fairly easy to learn to use quite effectively.

Given the fact I already have my great grandfather's slide rule, and he used one to fabricate plans for the building of the Empire State Building, do you all think I should learn to use it or pick up a new fancy-schmancy electronic calculator?