7 加法 21 等于多少？
7 + 21 = 28
7加法21 等于 28
竖式演算
验算
- 用减法验算：28 − 21 = 7
- 用减法验算：28 − 7 = 21
相关题目
7 + 20 = 27
7 + 22 = 29
7 + 19 = 26
7 + 23 = 30
7 + 24 = 31
7 + 18 = 25
7 + 25 = 32
7 + 17 = 24
6 + 21 = 27
8 + 21 = 29
5 + 21 = 26
9 + 21 = 30
4 + 21 = 25
10 + 21 = 31
11 + 21 = 32
3 + 21 = 24
1 + 27 = 28
2 + 26 = 28
3 + 25 = 28
4 + 24 = 28
5 + 23 = 28
6 + 22 = 28
20 + 44 = 64
31 + 14 = 45
10 + 17 = 27
15 + 34 = 49
1 + 23 = 24
72 + 24 = 96
82 - 54 = 28
79 - 51 = 28