小数简便运算的数学题我有7道不会的数学小数简便计算题!分别是：0.5×0.8×0.04×1.25×0.2×0.025/4

原式=(0.5×0.2)×(0.8×1.25)×(0.04×0.025)
=0.1×1×0.001
=0.0001
原式=(4.6÷4.6)×(72÷72)×(53÷53)
=1×1×1
=1
原式=（5.6÷0.7）×（16.5÷1.1）
=8×15
=120
原式=（152.3-31.15-21.15）×4.8
=100×4.8
=480
原式=2.4×7.6+6.5×7.6＋0.76＋7.6
=7.6×（2.4+6.5+0.1+1）
=7.6×10
=76
原式=6.3×27＋1.9×21
=7×0.9×3×9+1.9×3×7
=(7×3)×(0.9×9+1.9)
=21×10
=210
原式=0.0495×2500＋495×0.24+51×4.95
=495×（0.25+0.24+0.51）
=495×1
=495