While I was making this mental calculation a voice broke the silence.

As they left the building Elnora made a final rapid mental calculation.

He was singularly reflective, and seemed to be making a mental calculation.

He had made a quick mental calculation of the extent of the clearing.

He took out his watch and made a quick mental calculation.

Only after a rapid mental calculation could I account for her.

Pink blew a mouthful of smoke while he did a little mental calculation.

Frank looked at his watch and then made a mental calculation.

Zeena, while he spoke, seemed to be following out some elaborate mental calculation.

But mental calculation was laborious and he made a plunge:

I went leisurely through a small mental calculation, and said:

Percy hesitates a bit, and looks at the bookcases, and makes a mental calculation.

Aguirre, in his silence, seemed to be given over to a difficult mental calculation.

Seymour Michael so far forgot himself as to pause and make a mental calculation.

He stole sly glances at Dad and at Dave and made a mental calculation.

Nic did a quick mental calculation as Quin's vest flickered.