21 加法 7 等于多少？
21 + 7 = 28
21加法7 等于 28
竖式演算
验算
- 用减法验算：28 − 7 = 21
- 用减法验算：28 − 21 = 7
相关题目
21 + 6 = 27
21 + 8 = 29
21 + 5 = 26
21 + 9 = 30
21 + 4 = 25
21 + 10 = 31
21 + 11 = 32
21 + 3 = 24
20 + 7 = 27
22 + 7 = 29
19 + 7 = 26
23 + 7 = 30
24 + 7 = 31
18 + 7 = 25
25 + 7 = 32
17 + 7 = 24
1 + 27 = 28
2 + 26 = 28
3 + 25 = 28
4 + 24 = 28
5 + 23 = 28
6 + 22 = 28
46 + 13 = 59
10 + 66 = 76
1 + 12 = 13
87 + 10 = 97
10 + 2 = 12
2 + 23 = 25
44 - 16 = 28
29 - 1 = 28