①(8.3-3.26) ÷3.6×7.5
②4.19×3.6+7.4×4.19-4.19
③12.5×0.17×0.8×4
④1.35× (12.9-28.5÷3.8)
0.8×0.5=
3.2÷0.4=
2.5×8=
4.8÷0.06=
1.5×0.06=
0.52=
1.4÷7=
8×0.5÷0.5×8=
①3.09÷0.25×8
②47.6-7.6÷0.2
③11.75÷0.25÷0.4
④3.25÷[(7.6+1.5)÷7]
(3.2+0.56)÷0.8
8.8×12.5
0.36×23÷0.23
9.7-22.78÷3.4
9.6×25
3.6÷0.15+3.6÷0.25
7.3÷0.87.3 4.2×1.014.2
1.2×0.930.93 2.5÷1.12.5
①两个奇数的和是奇数;
②两个偶数的和是偶数;
③两个质数的和是质数;
④两个合数的和是合数。