1. 直接写出得数。
$1.2 - 0.5 =$ $0.4 + 6.9 =$ $1.2×0.7 =$
$250×4 =$ $150÷30 =$ $19.9×0.2 =$
$5.1 - 3.7 =$ $0.5×0.03 =$ $3.1×0.9 =$
$5.4 - 4.5 =$ $6.8 + 8 =$ $2.06 + 1.2 =$
$3 - 2.3 =$ $0.94 + 0.6 =$ $6.8 - 6.4 =$
$0.63 - 0.6 =$ $0.7 + 0.9 =$ $0÷25 =$

$1.2 - 0.5 = 0.7$
$0.4 + 6.9 = 7.3$
$1.2×0.7 = 0.84$
$250×4 = 1000$
$150÷30 = 5$
$19.9×0.2 = 3.98$
$5.1 - 3.7 = 1.4$
$0.5×0.03 = 0.015$
$3.1×0.9 = 2.79$
$5.4 - 4.5 = 0.9$
$6.8 + 8 = 14.8$
$2.06 + 1.2 = 3.26$
$3 - 2.3 = 0.7$
$0.94 + 0.6 = 1.54$
$6.8 - 6.4 = 0.4$
$0.63 - 0.6 = 0.03$
$0.7 + 0.9 = 1.6$
$0÷25 = 0$

2. 计算下列各题，能简算的要简算。
$14.5×64 + 64×5.5$ $1.47×(2 - 1.02) + 0.15$
$12.3×9.9$ $10.27 - (6.27 - 2.49)$
$2.6 + 1.4×3.5$ $0.125×7.8×80$

$14.5×64 + 64×5.5$
$=(14.5+5.5)×64$
$=20×64$
$=1280$
$1.47×(2 - 1.02) + 0.15$
$=1.47×0.98 + 0.15$
$=1.4406 + 0.15$
$=1.5906$
$12.3×9.9$
$=12.3×(10-0.1)$
$=12.3×10 - 12.3×0.1$
$=123 - 1.23$
$=121.77$
$10.27 - (6.27 - 2.49)$
$=10.27 - 6.27 + 2.49$
$=4 + 2.49$
$=6.49$
$2.6 + 1.4×3.5$
$=2.6 + 4.9$
$=7.5$
$0.125×7.8×80$
$=0.125×80×7.8$
$=10×7.8$
$=78$