It's unlucky to insert four candles on your 40th birthday.

It is unlucky to insert four candles on your 40th birthday, because in numerology, four is a bad number. If the number of candles ending in four is used at the birthday party, it will offend the joy of the whole birthday party and affect the health and fortune of the owner. Therefore, the ancient practice is usually four to five. For example, if you are thirty-four years old and celebrate your thirty-fifth birthday early, the candles are three big red candles and five small red candles. But from a scientific point of view, there is no such thing as "4 unlucky", and it can also be considered as twice as much as "2" and equivalent to "yes-man", so "4 unlucky" is a feudal superstition, so don't blindly believe it.