The smallest number which when added to 10000 becomes divisible by 20, 24 and 30 is

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CSIR-CLRI JSA 2024 Official Paper-I (Held On: 16 Feb, 2025)
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  1. 120
  2. 800
  3. 80
  4. 83

Answer (Detailed Solution Below)

Option 3 : 80
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Detailed Solution

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Given:

The smallest number which when added to 10000 becomes divisible by 20, 24, and 30.

Formula used:

Find LCM of 20, 24, and 30.

Calculation:

Prime Factorization:

20 = 22 × 5

24 = 23 × 3

30 = 2 × 3 × 5

LCM = 23 × 3 × 5 = 120

Find the smallest number added to 10000 that makes it divisible by 120:

10000 ÷ 120 = 83 remainder 40

To make the sum divisible by 120:

120 - 40 = 80

⇒ The smallest number is 80

∴ The correct answer is option (3).

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