6.47*52+64.7*4.8

6.47*52+64.7*4.8

6.47*52+64.7*4.8
=6.47×52+6.47×48
=6.47×（52+48）
=6.47×100
=647

How to do the simple method of 4.75 * 0.8 + 8 * 52.5

4.75*8+0.8*52.5
=4.75*8+8*5.25
=(4.75+5.25)*8
=10*8
=80

In order to facilitate calculation, people invented the abacus as early as that century. Who invented the abacus?

The origin of abacus can be traced back to 600 BC. It is said that there was a "abacus" in China at that time. The ancients strung 10 abacus beads into a group, arranged them in groups, put them into the frame, and then quickly moved them to calculate. In the end of the Eastern Han Dynasty, Xu Yue recorded in the book of numerology, when his teacher Liu Hong visited Mr. Tianmu, a hermit