Any member of the prism family.
Prism.
cubes, prisms, dodecahedrons...
A 400-sided polyhedron is called a "tetrahectahedron," though this term is not commonly used. In general, polyhedra are named based on the number of their faces, and for a 400-sided polyhedron, the prefix "hecta-" denotes its relation to the number 100. However, practical applications and discussions usually involve simpler polyhedra with fewer faces.
Any polyhedron other than a pyramid.
A shape that has fewer than 8 faces and fewer than 10 edges is a triangular prism. A triangular prism has 5 faces (2 triangular faces and 3 rectangular faces) and 9 edges. It meets the criteria of having fewer than 8 faces and fewer than 10 edges.
Prism.
Hexahedron
octahedron
A dodecahedron
cubes, prisms, dodecahedrons...
A 400-sided polyhedron is called a "tetrahectahedron," though this term is not commonly used. In general, polyhedra are named based on the number of their faces, and for a 400-sided polyhedron, the prefix "hecta-" denotes its relation to the number 100. However, practical applications and discussions usually involve simpler polyhedra with fewer faces.
Any polyhedron other than a pyramid.
A shape in fewer than 3 dimensions.A shape with one or more curved faces or edges.
There are 2 fewer faces.
A heptahedron is one possible answer.A heptahedron is one possible answer.A heptahedron is one possible answer.A heptahedron is one possible answer.
A pentahedron (eg square based pyramid) or a hexahedron (cuboid), or a heptahedron (a pentagon based prism). There are other shapes.
an octagon