解：3.72×49+37.2×5.1+49×51 ＝37.2×﹙4.9＋5.1﹚＋﹙50－1﹚×﹙50＋1﹚ ＝372＋2500－1 ＝2871.
3.72x(49+51)+49x51=3.72x100+(50-1)x51=372+51x50-51=372+2551-51=2871
