Is $8281$ the square of an odd number ?

Is $1296$ the square of an odd number ?

Evaluate ${39}^2-{38}^2$.

Evaluate ${86}^2-{85}^2$.

Evaluate ${101}^2-{100}^2$.

Evaluate ${134}^2-{133}^2$.

Evaluate ${192}^2-{191}^2$.

Evaluate ${247}^2-{246}^2$.

Without adding, find the sum.

$1+3+5+7+9+11$