First calculate the following questions orally and write the results directly.
36+25= 1+99÷9=
7×6÷×6= 57-34=
18 ÷ 3+40× 6 = (68-30) ÷ 2 =
17×3= 23-23×2×0=
56÷7= 17×2-6÷4=
Second, choose. What is the ultimate goal of the following questions? Fill in the serial number in brackets)
( 1)28×2→35÷5 [ ]
① quadrature; 2 seeking differences; 3 seek business.
(2)(80-43)÷4+2 [ ]
① seeking differences; 2 seeking business; 3 sum.
(3)20×3+ 15÷5 [ ]
① quadrature; 2 summation; 3 quotient.
(4)84×3-98+2 [ ]
(1) sum; 2 seeking differences; ③ quadrature
Third, the judge. (Is the following calculation correct? Mark "√" correctly in [] and "×" wrongly, and write the correct calculation process on the right).
( 1) 480÷6-42+7
=80-42
=38+7
=45[ ]
(2) 4+ 16÷4+ 16
=20÷20
= 1 [ ]
(3) 32÷8-32÷8
=4-4
=0 [ ]
Fourth, the following problems are not synchronized.
①27÷3 10 48 ÷ 6 ② 12× 4-8× 3
③52×6-24÷8