The approximate size of a nucleus in a typical mammalian cell is...

The length of the DNA double helix in a typical mammalian cell is calculated by multiplying the total number of base pairs with the distance between two consecutive base pairs.

Length of DNA = $6.6 \times 10^{9} \times 0.34 \times 10^{-9}$ m = $2.24$ m $\approx 2.2$ m.

The dimension of a typical mammalian nucleus is approximately $10^{-6}$ m.

Thus, the approximate size of a nucleus is $10^{-6}$ m and the length of the DNA molecule is $2.2$ m.

Answer: $10^{-6}$ and 2.2