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