unknown quantity

Still an unknown quantity: where Rockne S. O'Bannon's Cult will end up on the schedule.

But while Akerson may be an unknown quantity in Detroit, he is well-known to Whitacre.

Idly his pen traced upon the paper in front of him a large X, the sign of the unknown quantity.

Concerning farming, it is an unknown quantity here, as we in Australia understand it.

It seemed to her, in those days and afterward, that Allen symbolized the unknown quantity in all the problems that absorbed him.

In a case detailed by Casper, in which a boy drank an unknown quantity of acid, death took place in seven hours.

In most small towns, and especially in farm houses, a furnace is an unknown quantity.