What does it mean?

Using a computer (or a calculator inside a computer) to do simple math means letting the computer do addition, subtraction, multiplication, division — for us — instead of doing it by hand.

We tell it what we want (“5 + 3”, or “12 × 4”), and the computer gives the answer quickly.

Computers don’t “think” like us — they follow rules inside them (using 0s and 1s) to get the answer.

Why use a computer for math?

1. It’s faster — it can add many numbers quickly.


2. It’s more accurate — fewer mistakes if we input correctly.


3. It helps us to check if our manual answers are correct.


4. It lets us do more complex calculations we might be tired of doing by hand.

How a computer does math (in simple terms)

1. We input the numbers and the operation (like +, −, ×, ÷).


2. The machine converts what we typed into binary (0s and 1s) behind the scenes.


3. It applies arithmetic rules (like addition, subtraction) in binary form.


4. It converts back from binary to a number we understand (decimal).


5. It shows the result to us.

So even though we see “5 + 3 = 8”, inside the computer it might be doing “(binary for 5) + (binary for 3) = (binary for 8)”.

Steps to Use Calculator / Computer for Simple Math

1. Turn on the computer (or open the calculator app).


2. Choose the arithmetic mode (addition, subtraction, etc.).


3. Enter the first number.


4. Enter the operator (+, −, ×, ÷).


5. Enter the second number.


6. Press “=” or “Enter”.


7. The answer appears on the screen.


8. (Optional) If needed, you can continue with more operations (chain them).

Examples

1. Addition: Input: 25 + 17 → Output: 42


2. Multiplication: Input: 7 * 6 → Output: 42


3. You can try: 100 + 200 − 50 × 2 ÷ 5 and the computer will follow the correct order (BODMAS / PEMDAS).

Things to watch out for (cautions & tips)

1. Input correctly: Mistyping numbers or wrong operators leads to wrong answers.


2. Order of operations: The computer follows rules (× and ÷ before + and −) unless we use parentheses.


3. Division by zero: Never ask the computer to divide by 0 — it can’t do that (“undefined”).


4. Decimal and fraction results: Sometimes the result will have decimals (e.g. 7 ÷ 2 = 3.5).


5. Rounding errors: For very big or very small numbers, the computer may approximate the answer slightly.

Practice Problems to Try on a Computer

1. 45 + 28


2. 90 − 15


3. 12 * 11


4. 80 ÷ 5


5. 7 + 6 * 3 (check that the computer does multiplication first)


6. (7 + 6) * 3 (with parentheses)


7. 1000 ÷ 25


8. 123 + 456 − 78

After you see the answers, try doing them by hand (on paper) and compare.

Simple explanation

Imagine you have a magic box (the computer) that takes your numbers, does all the adding or multiplying inside secretly, and then gives you the result. You don’t need to do all the steps — you just tell it what to do, and it gives back the correct answer quickly.

But you must speak to it in the right way (type numbers and operators correctly), or it won’t understand.

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Meaning

A computer is an electronic machine that works by carrying out instructions given to it.
Everything that happens inside a computer — counting, adding, typing, showing pictures or music — is done using binary numbers (0s and 1s).

A binary number is a number written using only two digits: 0 and 1.

The relationship between a computer and binary numbers is that binary numbers are the language the computer understands.
Computers cannot understand letters or decimal numbers directly — they only understand binary code.

HOW COMPUTERS USE BINARY NUMBERS

Let us explain how binary connects to the computer step by step

1. Computers work with electricity



A computer is made up of electronic components (like transistors, resistors, and chips).

These parts work using electric current — when current flows, it means ON (1), and when there is no current, it means OFF (0).

So, everything that happens inside a computer can be represented as a series of ONs and OFFs → 1s and 0s.

That is why computers use binary numbers to represent data.

2. Binary represents everything inside the computer



Everything the computer stores or processes is converted into binary:

Letters (A, B, C, etc.) are converted into binary codes using ASCII.
Numbers (0–9) are converted into binary form before calculations.
Pictures, videos, and sounds are all stored as long strings of binary digits.

Example:
Letter “A” → 01000001
Number 5 → 101₂
Picture → a collection of binary codes for each pixel.

So, no matter what we give the computer, it changes it into binary before working on it.

3. Binary controls computer operations



Computers follow binary instructions (machine code).

For example:
00000001 may mean “Add”
00000010 may mean “Subtract”
00000011 may mean “Store data”

All computer programs and applications — games, Word, browsers — are made up of millions of such binary instructions.

Even though we write programs in English-like languages (Python, Java, etc.), the computer still translates them into binary machine code before execution.

4. Binary arithmetic



When you tell a computer to do calculations (like 2 + 3),
it converts 2 and 3 into binary (10₂ + 11₂),
performs the addition in binary,
and then converts the result back into decimal (101₂ → 5).

So, all arithmetic operations inside the computer — addition, subtraction, multiplication, and division — are done using binary arithmetic.

5. Binary is the foundation of computer data and storage



Every bit of information in a computer is made up of bits and bytes:

1 bit = a single binary digit (0 or 1)
1 byte = 8 bits (for example, 01001010)

Files, apps, and documents are stored using bytes, which are just long strings of 0s and 1s.

Example:
1 kilobyte (KB) = 1,024 bytes
1 megabyte (MB) = 1,024 KB
and so on.

So, your computer’s memory (e.g., 4GB RAM, 500GB storage) is actually measuring how many binary digits it can hold!

EXPLANATION

Imagine your computer is like a talking robot.
But the robot does not understand your language — it only understands light switches:

Light on = 1
Light off = 0

If you want it to say “Hello,” you must turn the right switches on and off in the correct pattern.
That pattern is called binary code.

So when you type letters, numbers, or pictures, your computer quickly changes them into the right pattern of 1s and 0s — and that’s how it “understands” you.

EXAMPLES

1. Letter A = 01000001₂


2. Number 5 = 101₂


3. Colour Red = 11111111 00000000 00000000 (in RGB binary)


4. Command Add = 00000001 (machine instruction)

SUMMARY

1. Computers work with electricity, which has only two states — ON and OFF.


2. ON and OFF are represented by 1 and 0 — this forms the binary system.


3. All data in a computer (letters, numbers, pictures, sounds) are represented in binary.


4. All computer operations are performed in binary form using binary arithmetic.


5. Binary is therefore called the language of the computer.

IMPORTANCE OF BINARY IN COMPUTERS

1. It helps computers to process data easily and quickly.


2. It allows computer engineers to design logic circuits that understand ON and OFF states.


3. It makes communication between hardware and software possible.


4. It is the foundation of all computer programming and digital systems.


5. Without binary, computers cannot function.

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Example words:

Let us use these few words:

CAT
DOG
HELLO

You see words — but your computer only sees numbers and binary digits (0s and 1s).

Let us go step by step

STEP 1: YOU TYPE THE WORDS

You press the keys:

C A T

Your computer sees letters — but it doesn’t know what a “C” or “A” looks like.
So, it needs to change them into numbers.

STEP 2: COMPUTER CONVERTS EACH LETTER INTO A NUMBER (ASCII CODE)

Every character (A–Z, a–z, numbers, punctuation) has a special number called ASCII code (American Standard Code for Information Interchange).

Letter	ASCII (Decimal)	Binary Code
C	67	01000011
A	65	01000001
T	84	01010100

So, the word CAT becomes:
01000011 01000001 01010100

That is what your computer stores in its memory!

STEP 3: COMPUTER USES BINARY ELECTRIC SIGNALS

Each 0 and 1 represents an electric signal:

1 = Electricity ON
0 = Electricity OFF

So, when the computer reads 01000011, it is actually reading a pattern of tiny electric pulses switching ON and OFF very fast.

Example (for letter C = 01000011):
OFF → ON → OFF → OFF → OFF → OFF → ON → ON

Those pulses are how the computer “feels” your letter C.

STEP 4: COMPUTER STORES AND PROCESSES THE BINARY

Now that the letters are in binary, the computer can:

1. Store them in memory


2. Send them to the screen


3. Compare them


4. Change them (for example, from small letter to capital letter)

It does all that by using logic circuits that only understand 0s and 1s (like little light switches).

STEP 5: COMPUTER CONVERTS BINARY BACK TO TEXT (FOR YOU TO SEE)

After finishing its work, the computer changes the binary code back into human-readable form (letters) so you can see CAT again on your screen.

It does the reverse process:

01000011 → C
01000001 → A
01010100 → T

EXPLANATION

Imagine your computer is a robot friend that only understands “light signals” —
light ON (1) and light OFF (0).

When you say “CAT,” you are really sending a pattern of lights to the robot:
💡💡💡💡 OFF–ON–OFF–OFF–OFF–OFF–ON–ON (for C)
and so on for A and T.

The robot does not see letters — it only sees the lights turning ON and OFF.
But when it finishes reading the pattern, it knows you meant “CAT” and shows it to you.

ANOTHER EXAMPLE: “DOG”

Letter	ASCII	Binary
D	68	01000100
O	79	01001111
G	71	01000111

So, DOG =
01000100 01001111 01000111

That is how your computer stores and understands the word “DOG”!

SUMMARY

1. Computers cannot understand letters or words directly.


2. Every letter has a unique number called its ASCII code.


3. Those numbers are converted into binary digits (0s and 1s).


4. Inside the computer, the binary digits are represented by electrical signals (ON and OFF).


5. The computer processes the binary data and later converts it back into readable letters on your screen.