1,420. Different Customs in Lighting

Hilchos Megillah v’Chanukah 4:2

Pursuant to the parameters described in halacha 4:1, if there are ten members of a household, on the first night of Chanukah one should light ten candles, one per person. On the second night, he should light 20; on the third night, 30. He continues in this manner until on the eighth night, he lights 80 candles.

Hilchos Megillah v’Chanukah 4:3

The common practice throughout Spain (where the Rambam lived) was to light a single candle for all the members of a household on the first night of Chanukah. They would then add a new candle on each subsequent night until, on the eighth night, eight candles were lit. This is so regardless of the size of the household, whether they are many or just one.