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### Abacus

Tools like the ABACUS have been used in the past for arithmetic.

##### Explanation

Always use your calculator in arithmetics. That prevents errors, and you save a lot of time. Do not be ashamed if you take your calculator even for simple tasks. Thereby you develop routine.

With a few keystrokes you can calculate formulas, which is, of course, very useful. Even better is if you can create charts. On better calculators you can calculate intersection points of curves.

In a few years you do not need separate calculators anymore, but can you calculate everything on your phone or tablet. With it you can look in math sites, and that makes it even easier.

##### Note

The table of Pythagoras was used to multiply quickly. Actually, the table is an extensive multiplication table in a different form.