Answer:
The atomic number of zirconium is 40. There is no need to round this number.
Step-by-step explanation:
Zirconium is a silver-white metal in the metallic state when purified and impure, malleable and ductile silver gray. It was discovered in the year 1789 by Klaproth, from the ore known as zircon. Its name comes from the Persian “zargum” which means golden in color due to the coloration of the aforementioned ore. It is a metal possessing properties similar to titanium, it is a transition metal belonging to the IVB family of the periodic table, its chemical symbol is Zr and it has the atomic number 40.