1
99:59:59,999 --> 99:59:59,999
1+3=4

2
99:59:59,999 --> 99:59:59,999
1+8=9

3
99:59:59,999 --> 99:59:59,999
10+2=12

4
99:59:59,999 --> 99:59:59,999
10+5=15

5
99:59:59,999 --> 99:59:59,999
10.21 因为2小于5

6
99:59:59,999 --> 99:59:59,999
10.21+3.35

7
99:59:59,999 --> 99:59:59,999
12+3=15

8
99:59:59,999 --> 99:59:59,999
19+3=22

9
99:59:59,999 --> 99:59:59,999
22英里

10
99:59:59,999 --> 99:59:59,999
3.35 近似为3英里

11
99:59:59,999 --> 99:59:59,999
3.89+5.1--

12
99:59:59,999 --> 99:59:59,999
4+5=9

13
99:59:59,999 --> 99:59:59,999
9+0=9

14
99:59:59,999 --> 99:59:59,999
9+10=19

15
99:59:59,999 --> 99:59:59,999
9+1=10

16
99:59:59,999 --> 99:59:59,999
9+3=12

17
99:59:59,999 --> 99:59:59,999
下面来计算一下准确数值

18
99:59:59,999 --> 99:59:59,999
不要误认为是这些加数的一部分

19
99:59:59,999 --> 99:59:59,999
先看百分位

20
99:59:59,999 --> 99:59:59,999
写2

21
99:59:59,999 --> 99:59:59,999
写5

22
99:59:59,999 --> 99:59:59,999
写5 进1

23
99:59:59,999 --> 99:59:59,999
向下拖动点

24
99:59:59,999 --> 99:59:59,999
因为1小于5 所以要下舍

25
99:59:59,999 --> 99:59:59,999
因为3比5小 还是要下舍

26
99:59:59,999 --> 99:59:59,999
在小数相加的时候一定要注意

27
99:59:59,999 --> 99:59:59,999
如果加起来的话 4+5=9

28
99:59:59,999 --> 99:59:59,999
我们的估算还是比较接近的

29
99:59:59,999 --> 99:59:59,999
所以她跑过的准确距离是22.55英里

30
99:59:59,999 --> 99:59:59,999
所以我的估算结果是4天来她跑了22英里

31
99:59:59,999 --> 99:59:59,999
把这些都加起来

32
99:59:59,999 --> 99:59:59,999
换个颜色

33
99:59:59,999 --> 99:59:59,999
然后1+1=2

34
99:59:59,999 --> 99:59:59,999
第二个数没有百分位 所以9+0+1=10

35
99:59:59,999 --> 99:59:59,999
要下舍到5英里

36
99:59:59,999 --> 99:59:59,999
要把小数点对齐

37
99:59:59,999 --> 99:59:59,999
误差比半英里多一点

38
99:59:59,999 --> 99:59:59,999
跟准确值非常接近

39
99:59:59,999 --> 99:59:59,999
近似为5英里

40
99:59:59,999 --> 99:59:59,999
近似成3英里

41
99:59:59,999 --> 99:59:59,999
还要注意

42
99:59:59,999 --> 99:59:59,999
这是我的估算结果

43
99:59:59,999 --> 99:59:59,999
这里是小数点

44
99:59:59,999 --> 99:59:59,999
进1

45
99:59:59,999 --> 99:59:59,999
进1

46
99:59:59,999 --> 99:59:59,999
进位写在上边

47
00:00:00,335 --> 00:00:07,886
珍奈尔正在为公路赛训练

48
00:00:07,886 --> 00:00:22,349
她的计步器记录了每天她跑的距离

49
00:00:22,365 --> 00:00:25,875
这是她四天来计步器的读数：

50
00:00:25,887 --> 00:00:33,995
周六 3.89英里 周日 5.1英里

51
00:00:34,009 --> 00:00:42,730
周一 10.21英里 周二 3.35英里

52
00:00:42,730 --> 00:00:44,920
估算四天来她跑的里程数

53
00:00:44,920 --> 00:00:51,070
然后计算出准确数值

54
00:00:51,130 --> 00:00:55,980
先来估算一下

55
00:00:55,980 --> 00:00:59,682
我就把它们都四舍五入取整

56
00:00:59,750 --> 00:01:06,933
3.89 约等于4英里

57
00:01:06,960 --> 00:01:10,172
因为十分位上

58
00:01:10,195 --> 00:01:14,910
是8 大于5

59
00:01:15,079 --> 00:01:21,669
所以大约就等于4英里

60
00:01:21,716 --> 00:01:28,416
然后看5.1