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དཔལ་ལྡན་འབྲུག་གཞུང་། ཤེས་རིག་དང་རིག་རྩལ་གོང་འཕེལ་ལྷན་ཁག།

Department of School Education

Ministry of Education & Skills Development

Python Coding

January 2024

Class X ICT Curriculum

January 2024

PYTHON

Key stage IV

Class X

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NESTED LOOPS

Key Concept #2

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Key stage IV

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Concept Overview

Coding Concept	Sub Concept
Nested Loops	for loop Nested loop while loop Looping using multiple conditions Nested loop Control statements in nested loops break, pass, continue Understanding loops through Turtle module

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Key stage IV

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Define nested loops with examples.
Apply correct syntax of nested loops in Python program.
Differentiate between nested for and while loop with examples.
Use nested loops in Python program to solve problems.
Apply pass, break and continue statements to control nested loops.
Draw shapes and patterns using nested loops in Turtle module.
Explain the importance of nested loops in Python programs.

Objectives

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Nested for Loop

ACTIVITIES

Understanding Nested for Loop
Demo 1 - Looping with Nested for Loop
Activity 1 - Nested for Loop
Activity 3 - Generate Pattern
Activity 4 - Nested Loop in Turtle Module

1

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Understanding for Loop

A for loop in Python is used to iterate over a sequence (such as a list, tuple, string, or range) or any other iterable object.
It repeatedly executes a block of code until the sequence is exhausted.

Code

for iterating_var in sequence:

statement(s)

Syntax

Hello

Output

1 2	for i in range(3): print("Hello")

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Key stage IV

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Flowchart

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Nested Loops

A nested loop is a loop inside a loop.
Nested loops are used to perform operations that require more than one level of iteration.
The inner loop is executed repeatedly for each iteration of the outer loop.

Nested Loops

Nested while loop

Nested for loop

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Nested for Loop

for loop is used for repeated execution of a group of statements for the desired number of times.
Nested for loop refers to the placement of a for loop inside a for loop.

for iterating_var in sequence:

statement(s)

Syntax

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Key stage IV

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Nested for Loop(cont.)

Code

1 2 3 4	for i in range(3): for j in range(2): print("inside",end=",")

Output

inside,inside,inside,inside,inside,inside,

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Key stage IV

Class X

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Flowchart for Nested for Loop

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Demo 1 - Looping with Nested for loop

Lets us see how nested for loop work.

1 2 3	for i in range(4): for j in range(2): print("Hello World!")

Code

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Key stage IV

Class X

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Demo 1 - Looping with Nested for Loop

Lets us see how nested for loop work.

1 2 3	for i in range(4): for j in range(2): print("Hello World!")

Code

Whatever is in this box, iit will execute four times.

Output

Hello World!

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Key stage IV

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Activity 1 - Combination of Two Dice

Two dice are rolled at the same time. Write a Python program to display all the possible combinations of the two dice. A sample output is given below (Hint: use nested for loops).

1 2 3 4 5 6	for i in range(1,7): for j in range(1,7): print(i,j," ", end=" ") print()

Code

Output

1 1 1 2 1 3 1 4 1 5 1 6

2 1 2 2 2 3 2 4 2 5 2 6

3 1 3 2 3 3 3 4 3 5 3 6

4 1 4 2 4 3 4 4 4 5 4 6

5 1 5 2 5 3 5 4 5 5 5 6

6 1 6 2 6 3 6 4 6 5 6 6

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Key stage IV

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Activity 2 - Multiplication Table of 2 and 3

Write a Python program to generate multiplication table of 2 and 3 upto 5. Sample output is given below.

1 2 3 4	for i in range(2, 4): for j in range(1, 6): print(i, "X", j, "=", i*j) print()

Output

2 X 1 = 2

2 X 2 = 4

2 X 3 = 6

2 X 4 = 8

2 X 5 = 10

3 X 1 = 3

3 X 2 = 6

3 X 3 = 9

3 X 4 = 12

3 X 5 = 15

Code

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Key stage IV

Class X

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Activity 3 - Generating Pattern

Write a Python program to generate pattern given below

*

* *

* * *

* * * *

* * * * *

Code

1 2 3 4 5 6	rows = 5 for i in range(0, rows): for j in range(0, i + 1): print("*", end=' ') print("\t")

Output

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Key stage IV

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Activity 3 - Printing Square Pattern

Write a Python program that uses nested for loops to print a square pattern made of asterisks .

Code

1 2 3 4	for i in range(4): for j in range(4): print("*", end=" ") print()

* * * *

Output

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Key stage IV

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Activity 4 - Nested Loop in Turtle Module

Write a Python program to generate pattern given below using Turtle module

Code

1 2 3 4 5 6 7	from turtle import * setup(150,150) for i in range(4): for j in range(4): forward(50) right(90) left(90)

Output

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Key stage IV

Class X

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Nested while Loop

ACTIVITIES

Understanding nested while loop
Activity 1 - Number Pattern using while Loop
Demo 1 - Nested while loop using Tracing Table
Activity 2- Tracing the code
Demo 2 - for loop using Turtle module
Activity 3 - Nested while loop

2

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Key stage IV

Class X

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While loop

while loop repeatedly carries out a target statement while the condition is true.
The loop iterates as long as the defined condition is True. When the condition becomes false, it will stop the iteration and execute the statements outside the loop.

while condition:

statement(s)

Syntax

Hello inside, Hello inside,

Output

Code

1 2 3 4	x=1 while x<3: print("Hello inside", end= “,”) x=x+1

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PYTHON

Key stage IV

Class X

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Flowchart for while Loop

START

Condition

Statement

STOP

Update

False

True

initialize

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Key stage IV

Class X

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Example 1 - while Loop with Multiple Conditions

Given below is the example of Python program, where while loop with multiple conditions are used.

20 15

15 11

10 7

5 3

1 2 3 4 5 6	i = 20 j = 15 while i > 0 and j > 0 : print(i,j) i -= 5 j -= 4

Output

Code

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PYTHON

Key stage IV

Class X

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Activity 1 - Printing Even Numbers below 40

Write a Python program that prints even numbers between 1 and 40 using a while loop with multiple conditions.

1 2 3 4	for num in range(2,40): while num<=40 and num%2==0: print(num, end=",") num+=1

Code

2,4,6,8,10,12,14,16,18,20,22,24,26,30,32,34,36,38,40

Output

January 2024

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Key stage IV

Class X

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Activity 1 - Printing Even Numbers below 40

Write a Python program that prints even numbers between 1 and 40 using a while loop with multiple conditions.

1 2 3 4	for num in range(2,40): while num<=40 and num%2==0: print(num, end=",") num+=1

Code

2,4,6,8,10,12,14,16,18,20,22,24,26,30,32,34,36,38,40

Output

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Key stage IV

Class X

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Activity 2 - Listing Multiples of 3 and 5

Write a Python program that prints numbers divisible by both 3 and 5 in the range from 1 to 100 using a while loop with multiple conditions.

1 2 3 4	for num in range(1,100): while num%3==0 and num%5==0: print(num, end=",") num+=1

Code

15,30,45,60,75,90

Output

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PYTHON

Key stage IV

Class X

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Nested while loop

Nested while loop is the loop structure where one while loop is placed inside another while loop.
It consist of an outer while loop that encloses an inner while loop.
The outer loop runs multiple times, and each time it runs, the inner loop also runs from start to finish.
The purpose of nested while loop is to perform more complex repetitive tasks.
In nested while loops, care must be taken to avoid infinite loops by ensuring proper conditions for both inner and outer loops.

January 2024

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Key stage IV

Class X

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Code

Inner loop

Outer loop

Output

while condition_outer:

# Body of outer loop

while condition_inner:

# Body of inner loop

Syntax

1 2 3 4 5 6 7 8 9	x=1 y=1 while x<3: while y<2: print("Inner loop") y=y+1 print("Outer loop") x=x+1

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PYTHON

Key stage IV

Class X

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Flowchart for Nested while Loop

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Demo 1 - Tracing a Nested while loop

Study the code given below and trace the output of the code.

Code

1 2 3 4 5 6 7	i = 1 while i <=2: j = 1 while j <= 2: print(i,”X”,j,”=”,i*j) j = j+1 i = i+1

Output

1 X 1 = 1

1 X 2 = 2

2 X 1 = 2

2 X 2 = 4

January 2024

PYTHON

Key stage IV

Class X

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Demo 1 - Tracing a Nested while loop

Study the code given below and trace the output of the code.

Code

1 2 3 4 5 6 7 8	i = 1 while i <=2: j = 1 while j <= 2: print(i,”X”,j,”=”,i*j) j = j+1 i = i+1

i	i<=2	j	j<=2	i*j	j=j+1	i=i+1
1	True	1	True	1	2	-
1	-	2	True	2	3	-
1	-	3	False	-	-	2
2	True	1	True	2	2	-
2	-	2	True	4	3	3
3	False	-	-	-	-	-

Output Tracing

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Activity 2 - Tracing the code

Study the code given below and trace the output.

Code

1 2 3 4 5 6 7	i = 1 while i <=2: j = 2 while j <= 3: print(i*j) j = j+1 i = i+1

i	i<=2	j	j<=3	i*j	j=j+1	i=i+1
1	True	2	True	2	3	-
1	-	3	True	3	4	-
1	-	4	False	-	-	2
2	True	2	True	4	3	-
2	-	3	True	6	4	3
3	False	-	-	-	-	-

Output

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Key stage IV

Class X

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Activity 3 - Nested while loop

Sonam wants to generate multiplication table of 1, 2 and 3 upto 10 using nested while loop. She wants your help on the following questions.

Writing an algorithm
Drawing a flowchart.
Writing a python program

January 2024

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Key stage IV

Class X

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Activity 3 - Solution

Algorithm

Flowchart

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Key stage IV

Class X

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Activity 3 Solution(cont.)

1 2 3 4 5 6 7 8	n = 1 while n <= 3: i = 1 while i <= 10: print(f"{n} X {i} = {n*i}") i += 1 print() n += 1

Code

January 2024

PYTHON

Key stage IV

Class X

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Nested Loops with Control Statement

ACTIVITIES

Understanding nested loop with Control Statement.
Activity 1 Break in Nested Loop
Activity 2 Continue in Nested Loop
Activity 3 - Pass in Nested loop
Activity 4 - Printing Number patterns

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PYTHON

Key stage IV

Class X

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Control Statements in Nested loops

Loop control statements are used to alter the normal flow of execution within loops.
Control statements helps to control the iteration process and modify the behaviour of the loop based on certain conditions.

Types of Control Flow Statements

break

pass

continue

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Key stage IV

Class X

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Break Statement

The break statement is used to terminate the loop prematurely. When encountered, it immediately exits the loop, regardless of whether the loop condition has been satisfied or not.

1 2 3 4 5 6	i = 1 while i < 6: print(i) if i ==3: break i += 1

Code

Example

i	i<=6	print(i)	if i==3	i=i+1
1	True	1	-	2
2	True	2	-	3
3	True	3	break	-

Output

January 2024

PYTHON

Key stage IV

Class X

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Continue Statement

The continue statement is used to skip the remaining code in the current iteration of the loop and move to the next iteration. It is often used when you want to skip certain iterations based on a condition and continue with the next iteration.

1 2 3 4 5 6	i = 0 while i < 6: i += 1 if i == 3: continue print(i)

1

2

4

5

6

Code

Output

Example

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PYTHON

Key stage IV

Class X

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Activity 2 Continue in Nested Loop

1 2 3 4 5	for i in range(1,3): for j in range(2): if i == j: continue print(i*j)

Study the code given below and trace the output .

Code

i	j	if i==j	i*j
1	0	False	0
1	1	True	-
2	0	False	0
2	1	False	2

Output Tracing

January 2024

PYTHON

Key stage IV

Class X

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Pass Statement

The pass statement is used as a placeholder when you need a statement syntactically correct but don't want any code to execute. It is commonly used as a placeholder for a block of code that you intend to implement later.

1 2 3	i = 1 while i < 6: pass

Code

Example

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Key stage IV

Class X

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January 2024

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Key stage IV

Class X

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Activity 4 - Printing Number Patterns

1 1 2 2 4 6 3 9 12 4 16 20 5 25 30 6 36 42 . . .

Study and identify the number pattern given below and write a python code using nested loop to generate number pattern.

1 2 3 4 5 6 7 8	i=1 j=1 while i<10: print(i,end="") while j<=i: print(" ",ij,"",ij+i,end=" ") j=j+1 i=i+1

Code

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PYTHON

Key stage IV

Class X

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A for loop is used to iterate over a known number of items in a sequence and the loop variable is automatically set to the next item on each iteration.
One loop can have another loop inside it and it is called nested loop.
A while loop is used to repeatedly execute a block of code as long as a certain condition is true. The condition is checked at the beginning of each iteration.
With break statement we can stop the loop before it has looped through all the items.
The continue keyword is used to end the current iteration in a for loop(or a while loop), and continues to the next iteration.

Key Points

January 2024

PYTHON

Key stage IV

Class X

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བཀྲིན་ཆེ།

THANK YOU

January 2024

PYTHON

Key stage IV

Class X