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- Question
Consider two-digit numbers which remain the same when the digits interchange their positions. What is the average of such two-digit numbers?
Options- A. 33
- B. 44
- C. 55
- D. 66
- Correct Answer
- 55
ExplanationAll such 2 digit numbers are 11,22,33,44....... upto 99
Forms an AP
So sum = n/2(a+l)
= 9/2(11+99)
Average = sum/9 = ½(11+99) = 55
- 1. Given that the polynomial (x2+ ax+ b) leaves that same remainder when by (x ?1) or (x + 1) What are the values of a and b respectively?
Options- A. 4 and 0
- B. 0 and 3
- C. 3 and 0
- D. 0 and any interger Discuss
- 2. A prime number contains the digit X at unit?s place. How many such digits of X are possible?
Options- A. 3
- B. 4
- C. 5
- D. 6 Discuss
- 3. The number 3521 is divided by 8. What is the remainder?
Options- A. 1
- B. 3
- C. 7
- D. 9 Discuss
- 4. For what value of X, 211X will be a perfect square?
Options- A. 4
- B. 5
- C. 6
- D. 9 Discuss
- 5. Product of three consecutive odd numbers is 1287. What is the largest of the three numbers?
Options- A. 9
- B. 11
- C. 13
- D. 17 Discuss
- 6. What is the sum of all prime numbers between 60 and 80?
Options- A. 272
- B. 284
- C. 351
- D. 414 Discuss
- 7. What is the unit place digit in the expansion of 773 ?
Options- A. 1
- B. 3
- C. 7
- D. 9 Discuss
- 8. Consider the following statements in respect of two integers p and q (both > 1) which are relatively prime: 1) Both p and q may be prime numbers. 2) Both p and q may be composite numbers 3) one of p and q may be prime and the other composite. Which of the above statements are correct?
Options- A. 1 and 2 only
- B. 2 and 3 only
- C. 1 and 3 only
- D. 1, 2 and 3 Discuss
- 9. Which one of the following is an irrational number?
Options- A. ?59059
- B. 231/593
- C. 0.454545....
- D. 0.121122111222 Discuss
- 10. How many pairs (A, B) are possible in the number 479865AB if the number is divisible by 9 and it is given that the last digit of the number is odd?
Options- A. 5
- B. 6
- C. 9
- D. 11 Discuss
Numbers problems
Search Results
Correct Answer: 0 and any interger
Explanation:
Since x^2+ ax + b when divided by x-1 or x+1 leaves the same remainder
So on putting x=1 and x=-1 we get the same value
1+a+b = 1-a+b
2a=0
a=0
here b can take any value as it will always get cancelled out
Correct Answer: 6
Explanation:
For prime no units place cannot be occupied by even number except for 2
Thus no of digits occupying unit digit of prime numbers = 6 (1,2,3,5,7,9)
Example 2,3,5,7,11,19 in itself are prime numbers
Correct Answer: 3
Correct Answer: 6
Correct Answer: 13
Correct Answer: 351
Correct Answer: 7
Correct Answer: 1, 2 and 3
Correct Answer: 0.121122111222
Correct Answer: 5
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