source: Before the invention of the pocket calculator, it was the most commonly used calculation tool in science and engineering
target: Before the pocket calculator it was the most used calculation tool in science and engineering.
references: Before the pocket calculator it was the most used calculation tool in science and engineering. Before the arrival of the pocket calculator, it was the most commonly used calculation tool in science and engineering. Before the arrival of the pocket calculator, it was the most commonly used calculation tool in science and engineering. Before the advent of the pocket calculator, it was the most commonly used calculation device in science and engineering. It was the most often used calculation tool in science and engineering before the invention of the pocket calculator. It was the most commonly used calculation tool in science and engineering before the pocket calculator. Before pocket calculators were created, it was the most used tool for doing math in science and engineering.