Friendly Numbers

NOTE

Mr. Gordon generated this programming puzzle using ChatGPT.

He then edited the results for clarity, accuracy, and brevity.

Specification

Two numbers are called friendly if the sum of the digits of both numbers is the same. For example, 123 and 213 are friendly because the sum of their digits is 1 + 2 + 3 = 6 for both.

Write a program that inputs a range of numbers and then counts how many numbers in that range are friendly with a given target number. The numbers in the range are more than zero and less than 1,000.

Input:

• The program first prompts for a target number (an integer).
• The program then prompts for the lower limit of the range (an integer).
• The program then prompts for the upper limit of the range (an integer).

Output:

• The program outputs the number of friendly numbers between the lower and upper limits (inclusive) that are friendly with the target number.

Examples

Sample Session 1

Event
Program Output	Enter target number:
User Input	123
Program Output	Enter lower limit of range:
User Input	100
Program Output	Enter upper limit of range:
User Input	200
Program Output	The number of friendly numbers between 100 and 200 with target number 123 is 6

Explanation

The target number is 123, whose digits, when added, have a sum of 6:

1 + 2 + 3 = 6

There are six numbers between 100 and 200 whose digits also have a sum of 6, which are:

• 105
• 114
• 123
• 132
• 141
• 150

Sample Session 2

Event
Program Output:	Enter target number
User Input:	55
Program Output:	Enter lower limit of range
User Input:	50
Program Output:	Enter upper limit of range
User Input:	60
Program Output:	The number of friendly numbers between 50 and 60 with target number 55 is 1

Explanation

The target number is 55, whose digits, when added, have a sum of 10:

5 + 5 = 10

There is only one number between 50 and 60 whose digits have a sum of 10. That number is 55.

Rating

This problem is somewhat spicy. Be sure you have reviewed how to use operators and loops.