Python For GCSE Computing

• Variable ________________________________________________ ________________________________________________

• Data type ________________________________________________ ________________________________________________

• Assignment ________________________________________________ ________________________________________________

• Casting ________________________________________________ ________________________________________________

• Input ________________________________________________ ________________________________________________

• Output ________________________________________________ ________________________________________________

• String ________________________________________________ ________________________________________________

Worked Examples

Example 1: Storing and displaying a value

python name = "Aisha" print(name)

1. "Aisha" is a string because it is inside quotation marks. 2. name = "Aisha" stores the string in the variable name. 3. print(name) displays the value stored in name. 4. The output is Aisha.

Now you try: Store "Python" in a variable called language, then display it.

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Example 2: Input and casting

python age = int(input("Enter your age: ")) next_year = age + 1 print(next_year)

1. input() asks the user for data. 2. int() changes the entered text into a whole number. 3. age + 1 can now be calculated. 4. print() displays the result.

Without int(), Python would treat the input as text and could not add 1 correctly.

Now you try: Ask for a person’s height as a decimal and display it.

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Example 3: Remainders

python number = 17 remainder = number % 5 print(remainder)

1. % finds the remainder after division. 2. 17 ÷ 5 leaves a remainder of 2. 3. Therefore, remainder stores 2.

Now you try: Find the remainder when 29 is divided by 4.

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Practice Questions

1. (Easy) What data type is stored in temperature = 21.5?

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2. (Easy) What does this output?

python x = 4 x = x + 3 print(x)

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3. (Medium) Explain why number = input("Enter a number: ") may cause a problem when used with number + 5.

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4. (Medium) Write Python code that asks for two integers and prints their total.

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5. (Medium) State the output of print(20 // 6) and print(20 % 6).

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6. (Hard) Write code that asks for a price and quantity, then displays the total cost.

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Answer Key

1. float. 2. 7. 3. input() returns a string, so Python cannot perform normal numeric addition. Use int(input(...)). 4. python first = int(input("Enter a number: ")) second = int(input("Enter another number: ")) print(first + second) 5. 20 // 6 gives 3; 20 % 6 gives 2. 6. python price = float(input("Enter the price: ")) quantity = int(input("Enter the quantity: ")) print(price * quantity)

Exam Tips & Common Mistakes

• Forgetting quotation marks: Text needs quotes, for example "Hello". Without them, Python treats the word as a variable. - Forgetting casting: Use int() for whole-number calculations and float() for decimal calculations. - Confusing = and ==: =

assigns a value; == compares two values. In an exam, use the operator that matches the task.

• Using the wrong data type: "15" is text, while 15 is an integer. Convert input before calculating. - Overwriting a useful value: If a variable is changed, its old value is lost. Use a second variable when both values are needed.

Examiner-focused tips:

• State the data type and explain what the value is used for, rather than only naming the variable. - When tracing code, write down each variable’s new value after every assignment. - If a question uses input(), check whether the result must be converted before arithmetic.

Quick Reference

Core rules

| Python code | Meaning | |---|---| | name = "Sam" | Stores text | | age = 15 | Stores an integer | | height = 1.72 | Stores a float | | passed = True | Stores a Boolean | | input("...") | Gets text from the user | | int(value) | Converts to an integer | | float(value) | Converts to a decimal | | str(value) | Converts to text | | print(value) | Displays a value | | a + b | Adds values | | a - b | Subtracts values | | a * b | Multiplies values | | a / b | Divides and can produce a decimal | | a // b | Whole-number division | | a % b | Remainder | | a ** b | Power |

Memory aid: V-C-I-O

• Variables store values. - Casting changes a data type. - Input is usually text. - Output is produced with print().

Absolute essentials

• Python runs instructions from top to bottom. - A variable name refers to a stored value. - int, float, str, and bool are common data types. - input() returns a string unless it is converted. - = assigns; == compares. - Use % for remainders and // for whole-number division.

Confidence Check

• I can explain how Python runs statements in order. [ ] 1 [ ] 2 [ ] 3 [ ] 4 [ ] 5 - I can identify int, float, str, and bool values. [ ] 1 [ ] 2 [ ] 3 [ ] 4 [ ] 5 - I can create and update a variable. [ ] 1 [ ] 2 [ ] 3 [ ] 4 [ ] 5 -

End of chapter one. 4 more chapters in the full book.