+4•[+12]

To solve the expression \( +4 \cdot [+12] \):

1. The notation \( [+12] \) means the absolute value of \( 12 \), which is simply \( 12 \) since it's already positive.
2. Therefore, the expression becomes \( +4 \cdot 12 \).

Now, calculate \( 4 \cdot 12 \):

\[ 4 \cdot 12 = 48 \]

So, \( +4 \cdot [+12] = 48 \).