How many eyes in potato to plant?

At least 2

2 to 3 eyes per piece.

I read on a site that you just plant the whole potato, it keeps bugs and other creepy crawlers from eating at the raw piece. Didn't do that this year, but gonna give it a try next year.

I always 1/4 the potato and yes leave 2-3 eyes

cut your potato in half, put each half in a bowl with water, it will grow eyes & it may take a week or two, but keep the water in the bowl. Wait for the eyes to appear, when more than 2 appear plant it in good dirt and watch it grow. You can also use seeds from apples, oranges, lemons cantelopes watermelon, I have also used the core from a bell pepper, you can plant that right away, I have gotten 2 plants from 3 bell pepper cores & one plant had a baby bell pepper on it, we snowbird and I had to leave it & it died. But if it is always watered and watched you can have a vegetable garden, my bell pepper plants were in containers.

Hope this helps & enjoy

Kathy