21 加法 9 等于多少？
21 + 9 = 30
21加法9 等于 30
竖式演算
验算
- 用减法验算：30 − 9 = 21
- 用减法验算：30 − 21 = 9
相关题目
21 + 8 = 29
21 + 10 = 31
21 + 11 = 32
21 + 7 = 28
21 + 12 = 33
21 + 6 = 27
21 + 13 = 34
21 + 5 = 26
20 + 9 = 29
22 + 9 = 31
19 + 9 = 28
23 + 9 = 32
24 + 9 = 33
18 + 9 = 27
25 + 9 = 34
17 + 9 = 26
1 + 29 = 30
2 + 28 = 30
3 + 27 = 30
4 + 26 = 30
5 + 25 = 30
6 + 24 = 30
34 + 18 = 52
91 + 20 = 111
18 + 66 = 84
53 + 72 = 125
91 + 17 = 108
65 + 5 = 70
6 × 5 = 30
51 - 21 = 30