The discovery and origin of mathematical knowledge To be brief, no more than 50 words 2. What kind of diseases are easily caused by insufficient oxygen and dirty air A. Respiratory system B, blood circulation system C, digestive system D, nervous system 3. Brazil and Australia are in the forefront of the world in terms of mineral resources, reserves and production

The discovery and origin of mathematical knowledge To be brief, no more than 50 words 2. What kind of diseases are easily caused by insufficient oxygen and dirty air A. Respiratory system B, blood circulation system C, digestive system D, nervous system 3. Brazil and Australia are in the forefront of the world in terms of mineral resources, reserves and production

1. Mathematics started from tying a rope to record events. About three million years ago, human beings were still in the primitive age of drinking blood, collecting wild fruits and hunting wild animals for a living. This kind of activity was often carried out collectively, and the "products" were equally distributed. In this way, the ancients gradually developed the concept of quantity
2. A.D if you choose one, it's d
3. Iron