Có abc1 - 1abc = 7506
=> abc x 10 + 1 - 1000 - abc x 1 = 7506
=> abc x ( 10 - 1 ) = 7506 + 1000 - 1
=> abc x 9 = 8505
=> abc = 8505 : 9
=> abc = 945
abc1-1abc=7506
=>abc*10+1-1000-abc*1=7506
=>abc*(10-1)=7506+1000-1
=>abc*9=8505
=>abc=8505:9
=>abc=945
Ta có: abc1-1abc=7506
abc*10-1000-abc=7506
abc*(10-1)-1000=7506
abc*9=7506+1000
abc*9=8506
abc=8506/9
abc=945,111111 ( dư )
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