Cube (algebra) however, easy to show that most numbers are not perfect cubes because "all" perfect cubes must have digital root 1, 8 or 9. That is their values modulo 9 may be only −1, 1 and 0. Moreover, the digital root of any number's cube can be determined by the remainder the number gives when divided by 3: Every positive integer can be written as the sum of nine (or fewer) positive cubes. This upper limit of nine cubes cannot be reduced because, for example, 23 cannot be written as the sum of fewer than nine positive cubes: The equation has
G.729 2 kbit/s steps. The G.729.1 uses three-stage coding: embedded Code-excited linear prediction (CELP) coding of the lower band, parametric coding of the higher band by Time-Domain Bandwidth Extension (TDBWE), and enhancement of the full band by a predictive transform coding by Time-Domain Aliasing Cancellation (TDAC). Bit rate and the obtained quality are adjustable by simple bitstream truncation. As of January 1, 2017, the patent terms of most licensed patents under the G.729 Consortium have expired, the remaining unexpired patents are usable on a royalty-free basis. G.729 includes patents from several companies which were until the expiry licensed by Sipro Lab