When lighting birthday candles, it is generally how many candles are inserted when you are old, or you can't insert too many candles when you are old. You can replace them with the first number or some lucky numbers you like. The custom of inserting candles on birthday cakes originated in ancient Greece. The admirers of Artimez, the ancient Greek goddess of the moon, would put cakes with candles on the altar when celebrating her birthday. Later, this custom gradually evolved into putting burning candles on children's birthday cakes and adding the content of blowing out candles.