9 加法 21 等于多少？
9 + 21 = 30
9加法21 等于 30
竖式演算
验算
- 用减法验算：30 − 21 = 9
- 用减法验算：30 − 9 = 21
相关题目
9 + 20 = 29
9 + 22 = 31
9 + 19 = 28
9 + 23 = 32
9 + 24 = 33
9 + 18 = 27
9 + 25 = 34
9 + 17 = 26
8 + 21 = 29
10 + 21 = 31
11 + 21 = 32
7 + 21 = 28
12 + 21 = 33
6 + 21 = 27
13 + 21 = 34
5 + 21 = 26
1 + 29 = 30
2 + 28 = 30
3 + 27 = 30
4 + 26 = 30
5 + 25 = 30
6 + 24 = 30
28 + 12 = 40
26 + 56 = 82
58 + 81 = 139
80 + 21 = 101
73 + 95 = 168
93 + 71 = 164
97 - 67 = 30
98 - 68 = 30