also: ななじゅう
numeric
seventy; 70
The number seventy. The reading しちじゅう is standard; ななじゅう is a common alternative, especially in spoken counting or to avoid confusion with いちじゅう. The reading ななそ is obsolete.
祖父は今年七十歳になります。
My grandfather will be seventy years old this year.
この本は七十ページあります。
This book has seventy pages.
Arabic numeral spelling, very common in horizontal writing and statistics.
Kanji numeral with 〇; occasionally seen in vertical writing or formal contexts.
Kana spelling for the reading ななじゅう; used for clarity or in children's materials.
Compound of 七 (seven) and 十 (ten). The reading しちじゅう is the regular on'yomi combination; ななじゅう uses the alternative kun'yomi-influenced reading of 七 for clarity.