Given that the three numbers are in the ratio 1:2:3, we can represent the numbers as $4x$, $8x$, and $12x$, where $x$ is a common multiplier.

The Highest Common Factor (HCF) of these numbers is given as 4. Since $x$ is multiplied by 4 in all the numbers, the HCF of the expressions $4x$, $8x$, and $12x$ is $4 \times \text{HCF of } x$.

This means:

$\text{HCF of } x = 1$

Thus, $x = 1$.

So, the three numbers are: $4x = 4 \times 1 = 4$ $8x = 8 \times 1 = 8$ $12x = 12 \times 1 = 12$

Therefore, the three numbers are 4, 8, and 12.

Would you like more details or have any questions?

Here are 5 related questions you might find interesting:

1. How would the problem change if the HCF was 6 instead of 4?
2. What is the least common multiple (LCM) of the numbers 4, 8, and 12?
3. If the ratio was 2:3:4 instead of 1:2:3, how would that affect the numbers?
4. How do you find the HCF of more than two numbers?
5. What is the sum of the three numbers 4, 8, and 12?

Tip: When dealing with ratios, remember that multiplying all terms by the same number preserves the ratio and scales the numbers proportionally.