However, when reproduced on the board, this new technique did not require mental trial-and-error computations nor complex carry memorization (unlike base 10 computations).

He does mental computations, such as those of chess,1 for example, which a normal would do in half an hour, in ten or fifteen seconds.

The following formula, when memorized, will permit mental computation of the day of the week on which any date falls:

He looked toward the collapsed barn, as if making a mental computation of its value, and then turned toward the farmer.

It is true that human minds manipulate symbols and engage in mental computations, as when doing arithmetic.

Austin did a quick mental computation.

Ryan paused long enough to do a quick mental computation.

I made a quick mental comPUtation.

He calculated quick mental computations regarding time, distance and what he must accomplish.

Richard Wakefield did some quick mental computations.