Two days back I read a news related to the tsunam which was,
A-23 foot and 23 foot. I think this is 23feet because of this is plural word.
But I couldn't understand "A-23 foot"
♥♦♣♠ NOT A TEACHER ♥♦♣♠
A 23-foot wave = a wave of 23 feet high.
When a numeral with an accompanying noun (in this case, 23 + feet) is used attributively (like an adjective) before another noun, you normally hyphenate the numeral and noun, and make the noun singular (not 23-feet, but 23-foot).