28 加法 21 等于多少？
28 + 21 = 49
28加法21 等于 49
竖式演算
验算
- 用减法验算：49 − 21 = 28
- 用减法验算：49 − 28 = 21
相关题目
28 + 20 = 48
28 + 22 = 50
28 + 19 = 47
28 + 23 = 51
28 + 24 = 52
28 + 18 = 46
28 + 25 = 53
28 + 17 = 45
29 + 21 = 50
27 + 21 = 48
30 + 21 = 51
26 + 21 = 47
31 + 21 = 52
25 + 21 = 46
32 + 21 = 53
24 + 21 = 45
1 + 48 = 49
2 + 47 = 49
3 + 46 = 49
4 + 45 = 49
5 + 44 = 49
6 + 43 = 49
23 + 10 = 33
5 + 50 = 55
60 + 100 = 160
3 + 20 = 23
56 + 32 = 88
60 + 23 = 83
80 - 31 = 49
68 - 19 = 49