a 10

a 10

Someone or something regarded as perfect or superlative in some way (as on a scale of 1 to 10). This weather is a 10 in my book—lots of sunshine with a cool breeze. A: "Wow, that girl is gorgeous." B: "I know, she's a real 10."
See also: 10
Farlex Dictionary of Idioms.

a ten

n. the highest rank on a scale of one to ten. On a scale of one to ten, this pizza’s a ten.
See also: ten
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • a ten
  • of its kind
  • bear a resemblance to
  • bear a resemblance to (someone or something)
  • be the living end
  • living end
  • living end, the
  • the living end
  • be the spit of
  • be the dead spit of (someone)
References in periodicals archive
Peter Carpenter, Director of Education for Aldar Academies said: "Across academies we have seen around a 10 per cent increase in the number of students achieving five A* to C, including in English and Mathematics.
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Results: Brotton A 5 (Darcy 1, Roe 2, Pashley 2), Ormesby D 5 (Wilkinson 3, Noutch 1); Ormesby A 10 (Young 3, Smith 3, Shaw 3), Tees Trains CIC Nomads 0; Ormesby C 4 (Ashwell 2, Childs 1, Muldoon 1), Nunthorpe A 6 (Walpole 3, Cooper 2); Nunthorpe B 4 (Lawton 3, Hildreth 1), Ormesby B 6 (Scott 2, Hitchen 2, Uppal 1).
Setback - despite a victory; Table tennis
Further, in Letter Ruling 8515041,(14) issued after the 1984 legislation, the IRS said that the seller must hold at least a 10 direct ownership in the acquiring corporation to obtain the benefits of Sec.
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