Question 28 (Choice 2) - Sample Paper 2 by Teachoo - Teachoo Sample Paper

Write a Python program to accept a positive integer n from the user and then print the following pattern using nested loops. For example, if n = 4, the output should be:

   1

  2 3

 4 5 6

7 8 9 10

Answer:

Answer by student

Detailed answer by teachoo

-lock-

To understand the Python program to print the pattern, we need to follow these steps:

• The program uses the input() function to accept a positive integer n from the user and converts it to an integer using the int() function.
• The program initializes a variable num with the value 1 , which is the current number to be printed in the pattern.
• The program uses a for loop to iterate from 1 to n using a variable i . The loop uses the range() function to generate a sequence of numbers from 1 to n , inclusive. For example, if n is 4 , the loop will run for i = 1, 2, 3, 4 .
• Inside the loop, the program prints (n - i) spaces before each row using the print() function with the end parameter set to "" , which means that nothing will be printed after the spaces. The program uses the multiplication operator ( * ) to repeat a string ( " " ) a number of times ( n - i ). For example, if n is 4 and i is 2 , the program will print " " twice.
• The program then uses another for loop to iterate from 1 to i using a variable j . The loop uses the same range() function as before. For example, if i is 3 , the loop will run for j = 1, 2, 3 .
• Inside the inner loop, the program prints the value of num followed by a space using the same print() function as before with the end parameter set to " " . For example, if num is 5 , the program will print "5 " .
• The program then increments the value of num by 1 using the += operator . This means that num becomes the next number to be printed in the pattern. For example, if num was 5 , it becomes 6 .
• After printing all the numbers in a row, the program prints a new line using the same print() function as before with no arguments. This means that a new line character ( \n ) will be printed after each row.
• The outer loop ends when i becomes equal to n , which means that all the rows of the pattern have been printed.

The final code is:

-endlock-