一、口算。
$80 + 9 =$
$10 + 60 =$
$64 - 60 =$
$85 - 5 =$
$38 - 8 =$
$2 + 80 =$
$3 + 60 =$
$9 + 50 =$
$60 - 40 =$
$35 - 30 =$
$45 - 5 =$
$70 + 6 =$
$6 + 50 =$
$20 + 50 =$
$58 - 8 =$
$90 - 70 =$
$43 - 40 =$
$50 + 4 =$
$4 + 30 =$
$80 + 7 =$
$79 - 70 =$
$32 - 30 =$
$92 - 90 =$
$4 + 90 =$
$70 + 7 =$
$5 + 60 =$
$57 - 50 =$
$80 - 20 =$
$61 - 60 =$
$80 + 6 =$

一、89 70 4
80 30 82
63 59 20
5 40 76
56 70 50
20 3 54
34 87 9
2 2 94
77 65 7
60 1 86

二、在$◯$里填“+”或“-”。
$60◯6 = 66$
$33◯30 = 3$
$27 = 7◯20$
$82◯2 = 80$
$30◯50 = 80$
$30 = 38◯8$
$70◯60 = 10$
$90◯2 = 92$
$4 = 84◯80$

二、+ - +
- + -
- + -