Do The Math To Solve These Clues

A number in a clue is usually a reference to another clue in the grid, or a Roman numeral.

Sometimes it is none of those.

Here are a few clues that use numbers as mathematical objects and symbols to stand for arithmetic operations.

Can you solve them?

 

From Alec Robins' book The A.B.C. Of Crosswords:

⅔ of 1 + ⅔ of 1 – what kind of sign is that? (4)

From Anatomy of the Crossword by D. St. P. Barnard:

Guardian 25037 (Puck):

Poor fish eaten by roughly 4.10 (11)

[Clues from the books have been kindly provided by Chaturvasi from his collection.]

Update 3-Sep-2014: Clue by Mohsin Ahmed @ 1ACross:

(twelfth of seventy-eight) + (fourth of five) + (eighth of eighteen) (3)

Related Posts:

• Roman Numerals
• Radio Alphabet in Crosswords
• Inter-grid References

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