用四舍五入法对下列各数按要求取近似数．
①9.23456（精确到0.0001）；
②567899（精确到百位）．
解：①9.23456≈9.2346（精确到0.0001）；
②567899≈5.679×105（精确到百位）．
My Tuesday Morning
Chinese class
8: 20 a.m. (上午)
English class
9:10 a.m.
Music class
10:20 a.m.
P. E.
11:10 a.m.
例：After Chinese class, I have English class.
Before English class, I have Chinese class.
如图，折叠直角三角形纸片的直角，使点C落在斜边AB上的点E处，已知AB=83，∠B=30°，则DE的长为( )
