As long as the potato is sprouting you can cut off the sprouted section of the potato and then plant the sprouted part of the potato in the ground.
Then eventually as long as you water the potato sprout you planted then the potatoes will grow more potatoes.
I've done this myself several times when I had store bought potatoes that were sprouting.
I would cut off the sprouted parts of the potato and then plant it and then cook the rest of the potato.
That way I then had more potatoes eventually from those sprouted potatoes.
I grow potatoes during the growing and warm season but also buy store bought potatoes and then in the spring plant the sprouted parts of the potato.