Another method, probably way too inefficient for jets:

(Altitude to lose / 1000) X 3 = NM distance from restriction to begin descent

Ground speed X 6 = Descent rate needed to make the restriction in the above calculated NM distance



Example:

Need to lose 10,000, and are currently 40 miles from restriction

(10,000 / 1000) X 3 = beginning of descent required 30 miles from restriction

400 KT Groundspeed X 6 = 2400 fpm descent rate required to lose 10,000 in 30 miles.