How many possible two-digit numbers can be formed by using the digits 3, 5 and 7 (repetition of digits is allowed)?a)10b)9c)7d)8Correct answer is option 'B'. Can you explain this answer?

Question

Answer

⇒ Number of possible two-digit numbers which can be formed by using the digits 3, 5 and 7 = 3 × 3.
∴ 9 possible two-digit numbers can be formed.
The 9 possible two-digit numbers are:
33, 35, 37, 53, 55, 57, 73, 75, 77

Answer

To find the number of possible two-digit numbers that can be formed using the digits 3, 5, and 7 (with repetition of digits allowed), we can use the concept of permutations with repetition.

Permutations with repetition is a way of counting the number of ways objects can be arranged when there are repeated objects. In this case, the repeated objects are the digits 3, 5, and 7.

Step 1: Identify the possible choices for each digit
In this case, the possible choices for each digit are 3, 5, and 7.

Step 2: Determine the number of choices for each digit
Since repetition of digits is allowed, each digit can be chosen from the set {3, 5, 7}. Therefore, there are 3 choices for each digit.

Step 3: Determine the total number of possible two-digit numbers
To find the total number of possible two-digit numbers, we need to multiply the number of choices for each digit.

3 choices for the tens digit * 3 choices for the ones digit = 9 possible two-digit numbers

Hence, the correct answer is option B) 9.

Similar SSC CGL Doubts

With a two digit prime number, if 18 is added, we get another prime number with digits reversed. How many such numbers are possible? (SSC CGL 2nd Sit. 2012)

In the number 76534218, each digit is replaced by the next digit i.e., 1 is replaced by 2, 2 is replaced by 3 and so on and then the digits are arranged in ascending order from left to right, which digit will be fifth from the left end?

If two is subtracted from each odd digit and three is added to each even digit in the number 3675249. How many digits will appear twice in the new number thus formed?

How many two-digit prime numbers are there between 10 and 100 which remain prime numbers when the order of their digits is reversed?

Top Courses for SSC CGLView all

General Awareness for SSC CGL

Lucent for GK

Quantitative Aptitude for SSC CGL

Current Affairs & Hindu Analysis: Daily, Weekly & Monthly

How to Prepare for SSC CGL

Top Courses for SSC CGL

Top Courses for SSC CGL

Suggested Free Tests

Related Content

Schools

Competitive Examinations

Quick Access Links

Technical Exams