known quantity

American  

noun

1. Mathematics. a quantity whose value is given: in algebra, frequently represented by a letter from the first part of the alphabet, as a, b, or c.

2. any factor, circumstance, etc., that is already accepted or familiar.

   Her honesty is a known quantity.

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Etymology

Origin of known quantity

First recorded in 1975–80

Example Sentences

In each case, Riley has opted to keep the known quantity.

From Los Angeles Times

Now a known quantity, Saints reduced their kicking to Caluori to deal with the breakout star's freakish aerial ability, while the teenager struggled to get the ball in hand to show his running power.

From BBC

Still, with some unknowns in the Chargers’ receiving corps outside of Ladd McConkey and Quentin Johnston, it makes sense that they would want to bolster their passing game with a more known quantity in a player such as Allen.

From Los Angeles Times

He is, in other words, a known quantity.

From Slate

As opposed to the much more “easy reader” version, which is bringing the same sensibility to the same music and feeling stuck but giving your fans a known quantity they can eat and consume year in and year out.

From Salon