# Perfect Computer Notes

Super Easy Short Computer Notes To Improve Computer Literacy and Your IT Skills

# Microsoft Excel Formulas To Calculate Your Age in Years Months Days and Day of Birth

Sometimes, a person needs the exact age calculation from his / her date of birth to a specific date, for example when he / she applies for a job. The employer demands the required age must not be more that 21 years on the given last date for submitting job application.
 Calculate your age from your date of birth in MS Excel with Datedif() function

In such situation,  we need to calculate exact date in years, months and days. Because the difference of  a single day will also be considered.
Today, we will learn, how to prepare Microsoft Excel Worksheet for calculating Age in Years, Months and Days with the help of formulas and functions provided in MS Excel. We will also find and display the actual day of birth from the given date of birth for a person.
 Age Calculator Designed in Microsoft Excel Using DATEDIF Function

### Preparation Of MS Excel Worksheet To Tell your Age from Date of Birth

1. First of all, start Microsoft Excel. Open a new blank workbook in MS Excel.
2. Type the data in MS EXCEL worksheet as shown in above figure.
3. You can perform any formatting on this worksheet with the help of different tools provided by Microsoft Excel like Font, Font Size, Font Color and Borders options.
4. Consider the following worksheet prepared to calculate Age from Date of Birth up to a given date.

### Inserting Formula Using DateDif( ) Built-in Excel Function for Age Calculation from Date of Birth

After entering the data in Microsoft Excel worksheet, it is a time to insert an Excel formula that will use mainly the DateDif( ) function for age calculation from date of birth.

For this purpose, we apply the required age calculation formula in the cell with cell reference D5.
First of all type = then type name of the function DateDif() and type the following formula in its parentheses.

## Formula of Age Calculation From Date of Birth in Excel

Type the following formula without any formatting and without line break in cell with cell reference D5.
=DATEDIF(B5,C5,"Y")&" Years, " & DATEDIF(B5,C5,"YM")&" Months, " & DATEDIF(B5,C5,"MD")&" Days"

1. Consider that,  line number 1 in blue color will produce the text 46 Years,
2. Second line with red maroon color will produce the text output  2 Months,
3. Ant the third line will produce text output 12 Days.

### Text Function Used to Display the Day of Birth as shown below in cell E5

=Text(B5,"dddd")
This function will return the day name on the given date in cell B5.

### DATEDIF( ) Function in MS EXCEL

Microsoft Excel provides a predefined function called DATEDIF(stands for date Difference) which will return the difference between two given dates in the form of years, months or days as required by the user.

### Syntax of DATEDIF( ) Function is as follows:

=DATEDIF(starting_date, ending_date, time_unit)

### The user will provide three arguments to DATEDIF function as follows:

•    starting_date - Starting date in Excel date serial number format.
•    ending_date - Ending date in Excel date serial number format.
•    unit - The time unit to use (years, months, or days). Actually, Y for years, M for months and D for days.

### Example of using DATEDIF( ) Function in Microsoft Excel

=DATEDIF (A1,B1,”Y”)
Let the cell A1 contains starting date 1/3/2016 (3-Jan-2016)
Let the cell B1 contains the ending date  2/4/2017 (4-Feb-2017)
The result of DATEDIFF( ) will be 1. Because there is one complete year btween two given dates.

Therefore,  DATEDIF function will calculate the time interval between a starting_date and an ending_date in years, months, or days. The time unit to return is specified using the unit argument. Unit argument can take the following 6 values in uppercase or lower case, as shown in the following table. Unit argument is provided in the following way:
 Age Calculation from Date of Birth in Excel Datedif()  function

Using Simple Formulas in Excel With Arithmetic Operators 2

# Create 3D Line Chart in MS EXCEL for 2 Cricket Teams

### Step 1: Open MS Excel

Open Microsoft Excel with a new blank Excel Workbook.

### Step 2: Type Sample Data in Excel Worksheet

Type data of two cricket teams as shown in the figure. Type data in 3 columns, Overs, Scores Team
A, and Scores Team B.
 Create 3 D line Chart in Microsoft Excel Easy Steps

### Step 3: Select Data for Chart

Select all data including the three columns from Overs to Score Team B.
 Select Data Create 3 D line Chart in Microsoft Excel Easy Steps

### Step 4: Click on Insert Tab

Click on Insert tab. Click on Line chart.
 Click Insert Tab Create 3 D line Chart in Microsoft Excel Easy Steps

### Step 5: Select 3-D Line Chart (Chart Type)

Select 3-D line chart from available chart type options.
 Select 3-D Line Chart Type Create 3 D line Chart in Microsoft Excel Easy Steps

### Step 6:  Select Chart Layout

Select a chart layout as shown in the figure. You will get the required 3-D line Chart in Microsoft Excel for analysis of scores two cricket teams time to time with respect to overs played.
 Select Chat Layout Create 3 D line Chart in Microsoft Excel Easy Steps

Using Simple Formulas in Excel With Arithmetic Operators 2

# Explain Different Security Threats To Computer Systems

## What is a Computer Security Threat?

A computer security threat may be defined as any action or event that may cause damage to any part of a computer system.
 Computer System Security Threats

## How Does Computer Security Threat Cause Damage?

A Computer security threat may cause damage to hardware, software, data , information or processing capability of a computer system.

## Different Types of Computer System Security Threat

There are many different types of security threats to computer systems as follows:

• Hacker
• Virus
• Worm
• Tech support scams
• Ransomware
• PUP Potentially Unwanted Software

## Hacker

Hacker is a person who uses computer system to access private data of illegally. Hackers access a computer network and its resources illegally.
 Hacker - Security Threats To Computer Systems and Networks

Hackers have a vast knowledge of computer science and are computer experts. They may have deep knowledge of  high level programming languages, low level programming language, operating systems, computer networks etc. But the problem is that they use their knowledge of computer science and computer systems for negative purpose. This purpose may be financial crimes through hacking online bank accounts or credit cards accounts of online users. Sometimes the purpose is only to annoy people or friends by hacking their social media accounts like face book accounts or twitter accounts. Sometimes hackers may hack email accounts also.

## Some Problems Caused by Hackers

• Hackers may steal the credit card numbers and other details for illegal use and can cause a lot of financial loss.
• Hackers may hack the email accounts of people to use without the knowledge of their users.
• Hackers try to access passwords so that they can access computer systems and intrude in the private networks illegally.
• Hackers may steal private data and information of people through their computer system hack for black mailing purposes.

## Virus

Computer Virus is a piece of code that can disturb the normal working of a computer system without
permission or without knowledge of the affected user. Computer viruses are the most common security threat to computer systems all over the world.
 Computer Virus- Security Threat To Computer System

Normally a virus will attach itself to a file. When the user executes this infected file, the virus is activated and create disturbance for the computer system working and for the user as well.

Moreover, when we transfer files from the infected flash drives, CDs, DVDs or portable hard drives, the virus is spread into other computer systems and networks.

MyDoom
AntiExe
Blaster
I LOVE YOU

## Problems Caused by Computer Virus

Viruses can:

• damage the files stored on infected computer systems
• affect the normal working process of computer systems
• delete data stored on disk storage
•  display unusual messages that annoy the user and disturb the normal working of the computer. These messages are shown on screen as alerts and user has to close that message dialog box before continue to his/her work.

## Worms

A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers.  A worm copies itself repeatedly in memory or on disk until there left no space. This enforces a computer to stop working.
 Computer Worm-Security Threats To Computer Systems

### Difference Between a Virus and Worm

Often, it uses a computer network to spread itself. Unlike a computer virus, it does not need to attach itself to an existing program.  Worms typically cause harm to their host networks by consuming bandwidth and overloading web servers. Whereas viruses almost always corrupt or modify files on a targeted computer.

• Melissa
• SQL Slammer
• Sasser
• The Blaster

### Problems Caused by Worm

• Slow down the computer system by consuming available memory
• Stop the computer working
• Some applications may stop working
• Destroy the files stored on infected computer systems

 Adware - Security Threats To Computer System

## Tech Support System Scams

Tech support scams use scare strategy to trick you into getting help from some fake online technical support people to help you remove fake errors in your system. They demand you for paying for unnecessary technical support services. These fake services may  apparently fix a device of your computer system, an operating system defect  or some other software errors.

 Technical Support SCAM - Security Threat To Computer Systems

These scams can use websites to attract you into contacting fake technical support people. Online users  may be redirected to these websites automatically because of  nasty ads found in doubtful sites. These fake websites may be some sites providing fake installers of pirated software, movies or games with serial numbers or hacked setups.

## Ransomware

Ransomware can restrict access to data by encrypting files. Sometimes, it may lock the computer screen for this purpose. It then attempts to obtain money by threat  from victims by asking for "ransom". The demand of the money is usually in form of crypt-currencies like Bitcoin.

 CryptoLocker Ransomware Security Threat to Computer Systems
Ransomware demand money in exchange for restoring access to encrypted data of the victim user.

## Unwanted software

Unwanted software are programs that may change your Operating system experience like Windows settings etc. without your knowledge or permission.

For example unwanted software when installed automatically as a side effect of installing some other software you just downloaded and installed from an authentic website, will change your browser settings. One example of change of browser setting is to change the default page or default search engine setting of the web browser. Moreover unwanted software may show ads that cannot be closed easily. A Potentially Unwanted Program, also called in short as PUP. PUP is a software that contains adware, installs toolbars or has other unclear objectives.

You must always download software from trusted websites. Install freeware carefully. Normally malicious freeware will ask your permission to install some other software too in default setup settings. Read carefully the instructions about license and cancel any new installations.