一个多边形的内角和是900°,则这个多边形的边数是( )
A:6
B:7
C:8
D:9
You must make him ____ (stop) that noise.
472-398=
1112 + 56 =
84.84 ÷ 0.84=
25% × 4=
5.2+8=
2.5-0.36-0.64=
625 × 512 =
5×4 ÷ 5×4=
3.54+0.74-2.54=
38 × 54 + 54 × 58 =