context: In 1742, a four-volume collected works of Johann Bernoulli was published. Sending him from Basel to Euler to Berlin, the old scientist wrote to his student: “I devoted myself to the childhood of higher mathematics. You, my friend, will continue its maturity. ” In the Berlin period, one after the other, Euler's works are published: “An Introduction to the Analysis of the Infinitesimals” (1748), “Marine Science” (1749), “The Theory of the Motion of the Moon” (1753), “A Manual on Differential Calculus” (Latin: Institutiones calculi differentialis, 1755). Numerous articles on selected issues are published in the publications of the Berlin and St. Petersburg Academies. In 1744, Euler discovered the calculus of variations. His works use thought-out terminology and mathematical symbolism, which have largely survived to this day, the presentation is brought to the level of practical algorithms.
question: When did the calculus first appear?
answers.text: 1744