Data processing is the process of converting raw fact (data) to information (processed data). It embraces the techniques of sorting, relating, interpreting and computing items of data in order to provide meaningful useful information.

## Steps in data processing

i) Preparation of source document: Here, figures, facts are obtained through different sources like name, age, sex, address of a student for a school

ii) Input of data: Once data is obtained from source document, it will be entered into the computer so that processing can take place. This can be done through the use of input devices like keyboard, mouse, scanner, microphone, etc.

iii) Manipulation of data: This step of data processing involves sorting and processing of data to obtain meaning information for example, in a school, students can be classified by class, age and admission number. All these classifications will produce results which maybe organized in form of summaries

iv) Output of information: The aim of data processing is to provide meaningful information, which can be obtained through different output media or devices like monitor, printer, speaker, etc.

v) Data Storage: In this step, the results of the processing are retained for future use or reference. Concrete devices in computing in the ancient times include the following.

(i) slide rule (ii) tally stick (iii) tally marks (iv) coins (v) ropes (vi) measuring rod (vii) Napier’s bone, etc.

## Tally stick

This is an ancient device used to aid person’s memory. It enhances recording of numbers, quantities and messages.

### Types of Tally

- Single Tally: This is an elongated piece of
**wood**that is marked with notches carved with a knife. - Split Tally: This is single tally that is split at a slight angle or curve in such a way that the halves are of different lengths. The longer halve called stock, is called foil and it is given to the buyer.
- Measuring Rod: This is an instrument that consists of a strip of
**wood**or metal or plastic with a straight edge that is used for drawing straight line and measuring length. Concept of number system in computing number system is a set of values used to represent different quantities. A number system can be used to represent number of students in a class or number of viewers watching a certain T.V programme. - Tally Mark: These are a form of numeral or little lines used for counting. They are also called harsh marks. They help in recording and sorting of data into classes. Tally marks are written in groups of free with the fifth line crossing over the first four.

## Different types of number system

- Denary/Decimal System
- Binary System
- Octal System
- Hexadecimal System

Denary System: This is based on ten digits (0,1,2,3,4,5,6,7,8,9). It is also called decimal system or base ten. Each digit can be expressed as a power of 10. For example 6823_{ten} can be expressed on power of 10 as 6 x 10^{3} + 8 x 10^{2} + 2 x 10^{1} + 3 x 10^{0}

Binary Number System: This is made up of two digits 0 and 1. It is a base 2 number system. The digits in a binary system can also be expressed as a power of 2. For example, 110101_{two} can be expressed as 1 x 2^{5} + 1 x 2^{4} + 0 x 2^{3} + 1 x 2^{2} + 0 x 2^{1} + 1 x 2^{0}

Octal Number System: This is made up of eight digits (0,1,2,3,4,5,6 and 7). It is also called base 8 system. Each digit position represents a power of 8. The right most digit represent 8^{0} = 1; followed by 8^{1} = 8; the 8^{2} = 64, etc.

The number 607_{eight} can be expressed as a power of 8 thus 6 x 8^{2} + 0 x 8^{1} + 7 x 8^{0}

Hexadecimal Number System

This system has 10 digits and 6 letters 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F, (A=10, B=11, C=12, D=13, E=14, F=15). It is also called a base 16 system. The position of each digit represents a power of 16.