①625×80-2520÷24，=50000-105，=49895；②（6+10.88÷3.2）×1.5，=（6+3.4）×1.5，=9.4×1.5，=14.1；③ 1 9 × 10 13 + 8 13 ÷ 9，= 1 9 × 10 13 + 8 13 × 1 9 ，=（ 10 13 + 8 13 ）× 1 9 ，= 18 13 × 1 9 ，= 2 13 ；④[（ 6 5 - 1 2 ）÷14]× 4 3 ...
(1/3+1/5)×15 =1/3×15+1/5×15 =5+3 =8 (1/9+1/3)×27 =1/9×27+1/3×27 =3+9 =12 (1/6+1/4)×36 =1/6×36+1/4×36 =6+9 =15 89×7/88 =(88+1)×7/88 =7+7/88 =7又7/88
1.2÷0.02=600.6+1.3=1.93.08×0.45=1.3869.88÷1.9=5.2验算：3.92÷3.7≈1.06
0.5+1.6=2.1 7.2-4=3.2 1+0.38=1.38 40×9=360 88+57=145 54÷3=18 2.9-0.7=2.2 392-83=309 25×6=150 6.5-3.5=3 16×5=80 3.4+2.7=6.1 0×340÷17=0 25×4+30=130 125×8×3=3000 1.2+1.8+0=3
69.8-(4.7+19.8)=(69.8-19.8)-4.7=50-4.7=45.3 4.74-8.98+15.98=4.74+(15.98-8.98)=4.74+7=11.74 2.5-1.98=2.5-(2-0.02)=2.5-2+0.02=0.52 7.2*9.9=7.2*(10-0.1)=72-0.72=71.28 7.2*10.1=7.2(10.0.1)=72+0.72=72.72 88.8*1.25=(80+8+0.8)*1.25=80...
①12.5×8.88=12.5×（1.11×8）=（12.5×8）×1.11=100×1.11=111②1.9+19.9+199.9+0.3=1.9+19.9+199.9+0.1+0.1+0.1=（1.9+0.1）+（19.9+0.1）+（199.9+0.1）=2+20+200=222③10.01×101-10.01=10.01×（101-1）=10.01×100=1001