- Reciprocal of \( 1 \): \( 1.0 \)
- Reciprocal of \( 0 \): \( \text{DNE} \)
- Reciprocal of \( -7 \): \( -\frac{1}{7} \)
- Reciprocal of \( \frac{7}{7} \): \( 1.0 \)
- Reciprocal of \( 3\frac{2}{5} \): \( \frac{5}{17} \)
- Reciprocal of \( -2\frac{4}{9} \): \( -\frac{9}{22} \)
Thus, the final boxed answers are:
\[
\boxed{1.0, \text{DNE}, -\frac{1}{7}, 1.0, \frac{5}{17}, -\frac{9}{22}}
\]