(9又1/7+6/7-)+(99又2/7+5/7)+(999又3/7+4/7-4/7)+(9999又4/7+3/7-3/7)+(99999又5/7+2/7-2/7)+(999999又6/7+1/7-1/7)
=10-6/7+100-5/7+1000-4/7+10000-3/7+100000-2/7+1000000-1/7
=1111110-(6/7+5/7+4/7+3/7+2/7+1/7)
=1111110-[(6+5+4+3+2+1)/7 ]
=1111110-3
=1111107
解:原式=10-6/7+100-5/7+1000-4/7+10000-3/7+100000-2/7+1000000-1/7
=(1000000+100000+10000+1000+100+10)-(1/7+2/7+3/7+4/7+5/7+6/7)
=1111110-3
=1111107