Quick Times

$32 \times 38 = 30 \times 40 + 2 \times 8$

$34 \times 36 = 30 \times 40 + 4 \times 6$

$56 \times 54 = 50 \times 60 + 6 \times4$

$73 \times77 = 70 \times80 + 3 \times7$

and so on?

Verify and generalise if possible.