Multiple choice

Which is the lowest number that has to be added to both 16 and 23 to make their HCF greater than 5?

  1. 2

  2. 3

  3. 4

  4. 5

  5. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Add 5: 16+5=21, 23+5=28. HCF of 21 and 28 is 7, which is > 5.

AI explanation

We must test the given options by adding each number to both 16 and 23, then finding the Highest Common Factor (HCF) of the resulting pair to see if it is greater than 5. Adding 5 gives the numbers 21 and 28, whose only common factors are 1 and 7. Since 7 is greater than 5, the HCF of the new pair of numbers is greater than 5. The lowest number to be added is 5.

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