BD的长是多少厘米．
怎样简便就怎样计算．
4.98+8.02×2.560.8﹣40.8÷2.50.8×69.6×12.5
4.98×99+4.96.48÷3.2÷2.51.2×7.6+7.6×6.8．
脱式计算，能简算的必须简算．
12.5×0.25×3204.57×0.36+4.57×0.64103×2.4
78.6÷12.5÷0.848×0.25×515.72÷（3.8﹣3.2×0.75）
递等式计算（能简算的要简便计算）．
3.6÷（3.6+1.2）， 26.18÷（5.2﹣3.5）+0.06（31.6﹣11.7）÷2.5÷0.4
[11÷（1﹣0.8）]÷0.120.12×48﹣201.2×1.4+2012×0.66．
递等式计算．（能简算的要简算）
9.6÷0.4×0.2529.7÷（5.85÷0.65）
7.4×9.93.84﹣2.7×0.64
8.68﹣8.68÷0.56×0.54.7×4.7+4.7+4.3×4.7．
7.85﹣4.7+2.15﹣4.3
193.2÷6.9﹣1.9×2.5
1.25×3.2×2.5×4.9
4.97×4.97+4.97×4.03+4.97
（3.12+0.9）÷（8.5﹣5×1.1）
[5+（17.9﹣1.74÷0.6）]×8.5．