The word calculator is derived from the Latin word calculates, which means to compute. This term was first used in the late 14th century. Nowadays, there are many different words used to refer to a calculator, pocket accountant, number cruncher, personal digital assistant, etc. Although we are all familiar with the small pocket devices used at school or work, there are many different types of calculators and reference tools. Some of these are:

Basic calculators
This is one of the most common types of calculators and can usually be used to perform four basic functions involving simple arithmetic. These are subtraction, addition, division, and multiplication.

Scientific calculators
This calculator is a must for students in middle and high school. The most well-known brand offering this type of calculator is Texas Instruments. It can be used for applications involving algebra, trigonometry, and geometry. They are widely used in the field of engineering, mathematics, and science. The first calculator of this type was manufactured in 1968 and was called HP-9100A.

Graphic calculators
These are a type of scientific calculator mostly used by those in college. They are a bit more advanced than scientific calculators and can perform more complex functions such as completing logarithms and plotting graphs.

Printing calculators
These calculators, in addition to calculating, also print details of the application performed and are a good choice for those that work with money. They can also be used in small shops to generate bills. They can work on either batteries or AC power. They were quite popular before the advent of computers. The data generated is usually shown in two colors black for positive and red for negative values.

Financial calculators
These devices are perfect for calculating financial details such as interest rates, cash flows, mortgage payments, and so on. They are a tool that is commonly used by accountants, realtors, and financial advisors.

Online calculators
Nearly all laptops and computers nowadays come with a calculator. Aside from that, there are many websites and apps that offer various types of calculators for various purposes. Some of these are:

Fitness and health calculators
These can be used to calculate body mass index (BMI), calorie intake, body fat, pregnancy conception, due date, and much more.

Math calculators
The options for these available online can be used to perform simple and complex mathematical operations. Some of these are fraction calculators, percentage calculators, and random number generators.

Others
In this category, there are many different online calculators, such as conversion calculators that can convert details from one unit of measurement to another. For example, from meters to centimeters. Time calculators can be used to calculate the time at a particular location or place. Age calculators can be used to determine the age of a person after inputting various necessary details. Other calculators in this category are password generators, GPA calculators, etc.

Citation machine
These are listed among calculators and reference tools and are mostly available online. They help ensure that professionals and students correctly credit the information that they are using in their research papers and other documents. Citations are especially important when writing papers for psychology as the American Psychological Association has specified a particular format. In this case, you can use any one of the following calculators and reference tools to ensure that you get it right:

KnightCite
Offered by Hekman Library at Calvin University, this tool can be used for a basic citation for a book. Ensure that you select APA from the styles available if citing from the behavioral and social sciences. You can also choose the MLA or Chicago style and pick from an array of text styles.

Zotero
This is a web browser add-on that can be used for various research purposes. It can help to keep track of your sources, organize your references and cite and share your findings.

APA Citation Wizards
This tool is quick and easy to use and can be used to create references for online books, journal articles, and web pages. However, do ensure that you are using the current edition in the publication manual for all citations, which is the seventh edition of the Publication Manual of the American Psychology Association that was released in 2019.

In addition to all the various types of calculators and reference tools mentioned above, let us not forget the handy phone calculators that most of us use when out with friends to split the bill. These devices have become essential in our modern daily lives.