Multiple choice

The HCF of two numbers is 21 and their LCM is 840. If one of the numbers is 105, find the other number.

  1. 111

  2. 800

  3. 168

  4. 222

  5. 467
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C Correct answer
Explanation

Product of two numbers = HCF * LCM. 105 * x = 21 * 840. x = (21 * 840) / 105 = 840 / 5 = 168.

AI explanation

We use the identity that the product of two numbers is equal to the product of their highest common factor and least common multiple. Setting up the equation, 105 multiplied by the unknown number equals 21 multiplied by 840. Dividing 17640 by 105 gives the other number, which is 168.

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