Calculator Accuracy & Usefulness

[Matt Agajanian]

Hi all.

Humour me, if you will, please.

Although HPs, TIs, Casios and Sharps were not like they are today in 2015, how vital, useful, essential were these scientific & programmable calculators in technical, scientific disciplines in the past even though they had 10 digit displays, limited algorithms, and, in TI's case 13-digit calculating precision at most?

Further, how useful, essential, reliable, etc. were HP Spice/Spike, Woostocks, V'Gers (yes, Voyagers), 41s in real engineering disciplines with their 10-digit accuracy?

Thanks in advance