489+798+897+696+45
=500-11+800-2+900-3+700-4+45
=500+800+900+700+(45一11一2一3一4)
=2900+25
=2925
489+798+897+696+45这么简算:
489+798+897+696+45=500-11+800-2+900-3+700-4+45
=500+800+900+700-11-2-3-4+45
=2900-20+45
=2900+25
=2925
489+798+897+696+45
=500-11+800-2+900-3+700-4+45
=500+800+900+700+45-2-3-11-4
=1200+800+900+[45-(2+3+11+4)]
=2900+25
=2925
=(500-11)+(700+98)+(700+197)+(700-4)+45
=2100+500=2600
=87+197-4+45
=(100-13)+(200-3)+41=300-16+41=325
=2600+325=2925。
489+798+897+696+45
=(500+800+900+700)+(45-11-2-3-4)
=2900+25
=2925