用简便方法计算:19+199+1999+19999+199999+1999999+......+1999个1999的和是多少?

要过程,要简便
2024-11-21 17:08:44
推荐回答(1个)
回答1:

19+199+1999+19999+199999+1999999+......+1999个1999
=(19+1+199+1+1999+1+19999+1+199999+1+1999999+1-6)+1999个1999
=(20+200+2000+20000+200000+2000000-6)+1999+1个1999+1-2
=(2222220-6)+2000个2000-2
=2222214+4000098
=6222312