估算.80÷19≈ 92÷30≈ 2390÷40≈ 632÷70≈724÷88≈ 2100÷68≈ 426÷60≈ 242÷31≈
x-x=18.7
15.8-(6+÷12.5%)
10-÷×1
325×0.36+6.75×36
5.6×0.375+×5.4-0.375×0.9