Abacus, an intelligent invention from ancestors, was commonly used in daily calculation in Japan, Taiwan, China and other Asian countries before the e …
Abacus, an intelligent invention from ancestors, was commonly used in daily calculation in Japan, Taiwan, China and other Asian countries before the e …
4 Math practice for elementary school first graders, including:- Basic add- Basic subtract- Advanced add- Advanced subtractEnjoy!免費玩First Graders Math …