Calculator
A calculator is a machine which allows people to do math operations more easily. For example, a normal calculator will add, subtract, multiply, and divide. Some also do square roots, and more complex calculators can help with calculus and draw function graphs. Calculators are found everywhere. A computer can act as a calculator.
Some calculators, like the abacus, will work without batteries. Others, like the electronic calculator, most of the time require batteries. There are two types of electronic calculators: simple calculators, which can only add, subtract, multiply and divide, and sometimes take square roots; and scientific calculators, which can do many other things, such as calculate factorials, sines and cosines.
There are different ways to write mathematics on a calculator. For example, after pressing "3" and then "+" and then "2" and then "=" (or "ENTER") the number "5" will be displayed on the screen. This is called infix notation. Many more advanced calculators use postfix notation, that is, "3 4 +" instead of "3 + 4 =". The third way of noting things, "+ 3 4", called prefix notation, is rarely found on calculators.
Pocket calculator [change]
A pocket calculator is a small calculator that helps people do mathematics. It is so small that it can be put in a pocket. Its most common use is for addition, subtraction, multiplication, and division. Pocket calculators are often powered by solar cells with a technology known as photovoltaics. They are commonly seen in schools and businesses around the world and can be used quickly and efficiently for simple mathematical problems. Another name for them is 'miniature calculator' or 'mini calculator'.
Scientific calculator [change]
A scientific calculator can do more things. It can often use exponents, pi, trigonometric ratios, and the order of operations. Scientific calculators can also use bigger numbers. They tend to cost more than pocket calculators.
