I usually do a batch with about 5 oranges at a time. However many fit into a small-med sized saucepan in one layer, snug fit best then they don't float.
Fit 4-5 oranges in a saucepan, cover with cold water.
Bring to the boil, then simmer for 15-20 mins.
Do this three times.
Make a thick sugar syrup - double sugar to water, then add in a big splash of water extra. Heat until dissolved sugar. (not sure how much you'll need, maybe start with 200g sugar, 100+ml water.)
Slice oranges thickly.
Add to sugar syrup. Oranges should be just covered. If not, just add extra water and sugar on top of oranges, heat to dissolve, and proceed as below.
Simmer on low heat until oranges go translucent. You know, that candied 'colour'? Usually takes 1-2 hours. Will get away with 1hr of cooking if rushed. Just will be a bit less candied. Will need to push oranges down into the syrup periodically.
Add extra water if evaporating and syrup is getting lowish.
Hope this makes sense!
Easy and yummy.