设百位数为x;个位数为y;则十位数=x+y-1
100x+10(x+y-1)+y=27(x+y+x+y-1) (1)
100y+10(x+y-1)+x=100x+10(x+y-1)+y+99 (2)
由(2)得:
99x-99y+99=0
x-y+1=0
y=x+1 (3)
代入(1)得:
100x+20x+x+1=27(2x+2x+2-1)
121x+1=108x+27
13x=26
x=2
y=3
x+y-1=4
所以,这个三位数为243
而342-243=99,所以,这个三位数为243
设百位数为x;个位数为y;则十位数=x+y-1
100x+10(x+y-1)+y=27(x+y+x+y-1) (1)
100y+10(x+y-1)+x=100x+10(x+y-1)+y+99 (2)
由(2)得:
99x-99y+99=0
x-y+1=0
y=x+1 (3)
代入(1)得:
100x+20x+x+1=27(2x+2x+2-1)
121x+1=108x+27
13x=26
x=2
y=3
x+y-1=4
所以,这个三位数为243
而342-243=99,所以,这个三位数为243