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- Question
Which of the following is not a prime number?
Options- A. 5
- B. 11
- C. 21
- D. 37
- Correct Answer
- 21
ExplanationA prime number is a whole number greater than 1 whose only factors are 1 and itself.
Factors of 5 are 1, 5
Factors of 11 are 1, 11
Factors of 21 are 1, 3, 7, 21
Factors of 37 are 1, 37.
Hence, according to the definition of a prime number, 21 is not a prime number as it has more than two factors.
- 1. A sequence of natural number 2,3,5,6,10. Such that no square and no cube occurs in the term. Find the 300th term of sequence ?
Options- A. 322
- B. 319
- C. 321
- D. 320 Discuss
- 2. How many digits will be there to the right of the decimal point in the product of 85.44 and .08455 ?
Options- A. 7
- B. 5
- C. 4
- D. 6 Discuss
- 3. A box contains 90 screws each of 100 gms and 100 bolts each of 150 gms. If the entire box weighs 35.5 kg, then the weight of the empty box is ?
Options- A. 10.5 kgs
- B. 12 kgs
- C. 9.6 kgs
- D. 11.5 kgs Discuss
- 4. What is the right most integer of the expression 65776759 + 54697467 ?
Options- A. 4
- B. 6
- C. 9
- D. 0 Discuss
- 5. A teacher multiplies 987 by a certain number and obtains 556781 as her answer. If in the answer, both 6 and 7 are wrong but the other digits are correct, then the correct answer will be
Options- A. 553681
- B. 555181
- C. 556581
- D. 555681 Discuss
- 6. If n is even, which of the following cannot be odd?
Options- A. n+3
- B. 2n
- C. n+4
- D. 3n Discuss
- 7. A perfect cube is an integer whose cube root is an integer. For example, 27, 64 and 125 are perfect cubes. If p and q are perfect cubes, which of the following will not necessarily be a perfect cube?
Options- A. 8p
- B. pq
- C. pq+27
- D. -p Discuss
- 8. What should be the maximum value of B in the following equation? 8A9 ? 6B2 + 4C6 = 723
Options- A. 4
- B. 1
- C. 5
- D. 7 Discuss
- 9. How many prime numbers exist in 65×359×113 ?
Options- A. 29
- B. 31
- C. 33
- D. 27 Discuss
- 10. There are several peacocks and deers in a cage (with no other types of animals). There are 72 heads and 200 feet inside the cage. How many peacocks are there, and how many deers ?
Options- A. 42 & 24
- B. 38 & 26
- C. 36 & 24
- D. 44 & 28 Discuss
Numbers problems
Search Results
Correct Answer: 320
Explanation:
1 to 300 = 300 numbers
squares btwn 1 to 300 = 1,4,9,16,25,36,49.....289 i.e, total 17
cubes = 1,8,27,64,125,216 i.e, 5
now 1 and 64 are common so total numbers that should be removed ( 17+5-2= 20 )
total 20 term removed so 300th term would be 320
Correct Answer: 6
Explanation:
Sum of decimal places = 7.
Since the last digit to the extreme right will be zero (since 4 x 5 = 20), so there will be 6 significant digits to the right of the decimal point.
Correct Answer: 11.5 kgs
Explanation:
Screws weight = 90x100 = 9000gms
bolts weight = 100 x 150 = 15000gms
weight = screws + bolts => 24000 gms =>24 kg
Given entire box weight = 35.5kg
empty box = entire box weight - weight => 35.5kg - 24kg => 11.5kg
so the empty box is 11.5kg.
Correct Answer: 9
Explanation:
Last digit for the power of 6 is 6 (always)
Power cycle of 7 is 7, 9, 3, 1.
Now 467/4 gives a remainder of 3
Then the last digit is = 3
Last digit is 6 + 3 = 9.
Correct Answer: 555681
Explanation:
Given number is 987 = 3 x 7 x 47.
So, required number must be divisible by each one of 3, 7, 47.
None of the numbers in 553681 and 555181 are divisible by 3. While 556581 is not divisible by 7.
Correct answer is 555681.
Correct Answer: 2n
Explanation:
In case B, odd times even will give even
Correct Answer: pq+27
Explanation:
A perfect cube will have prime factors that are in groups of 3; for example 125 has the prime factors 5 x 5 x 5 , and 64 x 125 will also be a cube because its factors will be 4 x 4 x 4 x 5 x 5 x 5
Consider the answer choices in turn.
8 is the cube of 2, and p is a cube, and so the product will also be a cube.
pq will also be a cube as shown above.
pq is a cube and so is 27, but their sum need not be a cube. Consider the case where p =1 and q = 8, the sum of pq and 27 will be 35 which has factors 5 x 7 and is not a cube.
-p will be a cube.
Since the difference between p and q is raised to the power of 6, this expression will be a cube (with cube root = difference squared).
Correct Answer: 7
Explanation:
1 1
8 A 9
+ 4 C 6
- 6 B 2
7 2 3
We may represent the given sum, as shown below:
1 + A + C - B = 12
A + C - B = 11
Now,giving the maximum values to A and C, i.e.
A = 9 and C = 9, we get B = 7.
Correct Answer: 31
Explanation:
Given
Thus, there are (5 + 5 + 9 + 9 + 3)= 31 prime numbers.
Correct Answer: 44 & 28
Explanation:
Let
x = peacocks
y = deers
2x + 4y = 200
x + y = 72
y = 72 - x
2x + 288 - 4x = 200
x = 44 peacocks
y = 28 deers
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