Class 8 Exam > Class 8 Questions > The sum of the digits of a two number is 9. I... Start Learning for Free
The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?
- a)54
- b)63
- c)72
- d)45
Correct answer is option 'A'. Can you explain this answer?
Most Upvoted Answer
The sum of the digits of a two number is 9. If 9 is subtracted from th...
Let the unit’s digit be x.
Ten’s digit = 9 – x
Number = 10 (9 – x) + 1(x)
= 90 – 10x + x= 90 – 9x
90 – 9x – 9 = x(10) + 1(9 – x)
⇒ 81 – 9x = 10x + 9 – x
⇒ 81 – 9x = 9x + 9
⇒ 18x = 72 ⇒ x = 4
Number = 90 – 9 × 4 = 90 – 36 = 54
Ten’s digit = 9 – x
Number = 10 (9 – x) + 1(x)
= 90 – 10x + x= 90 – 9x
90 – 9x – 9 = x(10) + 1(9 – x)
⇒ 81 – 9x = 10x + 9 – x
⇒ 81 – 9x = 9x + 9
⇒ 18x = 72 ⇒ x = 4
Number = 90 – 9 × 4 = 90 – 36 = 54
Free Test
FREE
| Start Free Test |
Community Answer
The sum of the digits of a two number is 9. If 9 is subtracted from th...
Explanation:
Let's assume that the two digits are x and y.
According to the question, the sum of the digits is 9, so we can write:
x + y = 9 ---(1)
If 9 is subtracted from the number, its digits are interchanged. This means that the original number is a multiple of 9. Let's represent the original number as 10x + y.
When 9 is subtracted from the original number, we get:
10x + y - 9 = 10y + x
Simplifying the above equation, we get:
9x - 9y = 9(x - y) = 9
Dividing both sides by 9, we get:
x - y = 1 ---(2)
Now, we have two equations (1) and (2) with two variables (x and y). We can solve for x and y using these equations.
Adding equations (1) and (2), we get:
2x = 10
x = 5
Substituting the value of x in equation (1), we get:
y = 4
Therefore, the two digits are 5 and 4, and the original number is 54.
Hence, the correct answer is option A.
Let's assume that the two digits are x and y.
According to the question, the sum of the digits is 9, so we can write:
x + y = 9 ---(1)
If 9 is subtracted from the number, its digits are interchanged. This means that the original number is a multiple of 9. Let's represent the original number as 10x + y.
When 9 is subtracted from the original number, we get:
10x + y - 9 = 10y + x
Simplifying the above equation, we get:
9x - 9y = 9(x - y) = 9
Dividing both sides by 9, we get:
x - y = 1 ---(2)
Now, we have two equations (1) and (2) with two variables (x and y). We can solve for x and y using these equations.
Adding equations (1) and (2), we get:
2x = 10
x = 5
Substituting the value of x in equation (1), we get:
y = 4
Therefore, the two digits are 5 and 4, and the original number is 54.
Hence, the correct answer is option A.
 | Explore Courses for Class 8 exam |  |
Top Courses for Class 8View all
Top Courses for Class 8
Question Description
The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? for Class 8 2026 is part of Class 8 preparation. The Question and answers have been prepared according to the Class 8 exam syllabus. Information about The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Class 8 2026 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer?.
The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? for Class 8 2026 is part of Class 8 preparation. The Question and answers have been prepared according to the Class 8 exam syllabus. Information about The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Class 8 2026 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer?.
Solutions for The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for Class 8. Download more important topics, notes, lectures and mock test series for Class 8 Exam by signing up for free.
Here you can find the meaning of The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer?, a detailed solution for The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? has been provided alongside types of The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice The sum of the digits of a two number is 9. If 9 is subtracted from the number its digits are interchanged. What is the number?a)54b)63c)72d)45Correct answer is option 'A'. Can you explain this answer? tests, examples and also practice Class 8 tests.
| Explore Courses for Class 8 exam | |
Top Courses for Class 8
Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
