The factors of 56 are [1, 2, 4, 7, 8, 14, 28, 56] and the factors of 16 are [1, 2, 4, 8, 16]. They share 4 factors [1, 2, 4, 8] making 8 the greatest factor 56 and 16 have in common.

The first few multiples of 4 are [4, 8, 12, 16, 20, 24, 28, 32, 36, 40] and the first few multiples of 6 are [6, 12, 18, 24, 30, 36, 42, 48, 54, 60]. The first few multiples they share are [12, 24, 36, 48, 60] making 12 the smallest multiple 4 and 6 have in common.

A factor is a positive integer that divides evenly into a given number. For example, the factors of 8 are 1, 2, 4, and 8.

To simplify a radical, factor out the perfect squares:

\( \sqrt{63} \)
\( \sqrt{9 \times 7} \)
\( \sqrt{3^2 \times 7} \)
3\( \sqrt{7} \)

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{12 + 4 + 10 + 6}{4} \) = \( \frac{32}{4} \) = 8