计算:123+234+345+456+567+678+789=_.
问题描述:
计算:123+234+345+456+567+678+789=______.
答
123+234+345+456+567+678+789,
=(100+200+300+400+500+600+700)+(20+30+40+50+60+70+80)+(3+4+5+6+7+8+9),
=2800+350+42,
=3192.
故答案为:3192.