A | 13 |
A | 14 |
A | 44 |
②因为0是特殊元素,分两类,个位数字是0,和不是0,
当个位数是0,有
A | 55 |
当个位不数是0,有
A | 14 |
•A | 14 |
A | 44 |
③当千位小于4时,有
A | 12 |
A | 13 |
A | 24 |
A | 24 |
A | 12 |
当千位是4,百位小于3时,有
A | 13 |
A | 22 |
A | 12 |
•A | 13 |
当千位是4,百位是3,十位小于1时,有1种,
当千位是4,百位是3,十位是1,个位小于等于0时,有1种,
所以不大于4310的四位偶数4有96+24+12+1+1=110
A | 13 |
A | 14 |
A | 44 |
A | 55 |
A | 14 |
•A | 14 |
A | 44 |
A | 12 |
A | 13 |
A | 24 |
A | 24 |
A | 12 |
A | 13 |
A | 22 |
A | 12 |
•A | 13 |