The front-runners are not the only ones facing some difficult political calculations.

Cameron says this is a "very difficult" calculation.

Guide your young friend around the various worlds and rescue numbers in the correct order, solve more difficult calculations and get bonus points.

California, with its numerous delegates and expensive media market, makes that calculation all the more difficult.

This is considered a difficult calculation.

The state prosecutors today faced a difficult legal calculation.

The correct, and far more difficult calculation, is the "cradle to the grave" calculation.

The difficult calculations there beginning to pay off.

By simplifying difficult calculations, logarithms contributed to the advance of science, and especially of astronomy.

In my case this would be a difficult calculation.