Confirming device contains only zeros

I have wiped several hard drives with either dc3dd or dcfldd and would like to check if they are indeed wiped with zeros. I would like to not scroll through page after page of zeros, but only see the first line and any line thereafter with data other than zero. My commands were:
sudo dc3dd hwipe=/dev/sda hash=md5
sudo dcfldd if=/dev/zero of=/dev/sda bs=8k

Would using xxd or hexdump confirm the above?