>>88853167Similar but not the same.
Maru is the equivalent to saying "oh" in english to indicate the empty space in a big number like a date, like twenty-oh-nine.
Rei is similar, being used roughly the same way as the english "nought." It's an archaic word for 'nothingess' (largely in a spiritual sense) and is almost never said aloud, only serving to essentially be the placeholder kanji for zero so it doesn't need to be written out in kana every time--which is also largely obsolete since zero can just be written as 0. Rei is one of those terms that exists in theory but isn't used in practice unless it's someone using flowery language or talking about the spiritual concept of nothingness. outside of a mathematical sense
