Numbers Questions Answers

• 15. 587 * 999 = ?

  1. 586411
  2. 586413
  3. 486411
  4. 486413

  Answer And Explanation

  Answer: Option B

  Explanation:

  Trick: 587 * (1000 - 1) = 587000 - 587 = 586413

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• 16. 469157 * 9999

  1. 1691100843
  2. 4591100843
  3. 4691100843
  4. 3691100843

  Answer And Explanation

  Answer: Option C

  Explanation:

  469157 * (10000 - 1)
  = 4691570000 - 469157
  = 4691100843

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• 17. 1307 * 1307 = ?

  1. 1608249
  2. 1508249
  3. 1408249
  4. 1708249

  Answer And Explanation

  Answer: Option D

  Explanation:

  \begin{aligned}
  (a + b)^{2} = (a^2 + b^2 + 2ab)
  \end{aligned}
  \begin{aligned}
  1307^{2} = (1300 + 7)^2 = (1690000 + 49 + 18200)
  \end{aligned}

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• 18. 217 * 217 + 183 * 183

  1. 70578
  2. 82578
  3. 80578
  4. 80568

  Answer And Explanation

  Answer: Option C

  Explanation:

  \begin{aligned}
  \frac {1}{2}\times 2(a^2 + b^2) = \frac {1}{2} \times [(a + b)^2 + (a - b)^2]
  \end{aligned}
  \begin{aligned}
  = \frac {1}{2} \times [(217 + 183)^2 + (217 - 183)^2] = 80578
  \end{aligned}

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• 19. For the integer n, if n*n*n is odd, then what is true

  1. n is odd and n*n is even
  2. n*n is odd
  3. n is even
  4. n*n is odd

  Answer And Explanation

  Answer: Option A

  Explanation:

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• 20. There are four prime numbers written in ascending order. The product of first three is 385 and that of last three is 1001. The last number is:

  1. 9
  2. 13
  3. 15
  4. 12

  Answer And Explanation

  Answer: Option B

  Explanation:

  \begin{aligned} \frac{abc}{bcd} = \frac{385}{1001} => \frac{a}{d} = \frac{5}{13} \end{aligned}So d = 13

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• 21. \begin{aligned}
  46^2 - (?)^2 = 4398 - 3066
  \end{aligned}

  1. 23
  2. 18
  3. 38
  4. 28

  Answer And Explanation

  Answer: Option D

  Explanation:

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