Question

which is a longer length 10.5 mm or 0.105 dm they are the same length. 0.015 dm 10.5 mm

Explanation:

Step1: Convert dm to mm

Recall that $1\ \text{dm} = 100\ \text{mm}$. So:
$0.105\ \text{dm} = 0.105 \times 100\ \text{mm} = 10.5\ \text{mm}$

Step2: Compare the two lengths

Both values equal $10.5\ \text{mm}$.

Answer:

They are the same length.