Ta có số `A=bar(abc);B=bar(abcabc)`
Ta có phép tính:
`B÷7÷11÷13=A`
`B÷(7×11×13)=A`
`B÷1001=A`
`=>bar(abcabc)÷1001=bar(abc)`
`bar(abcabc)`
`=(100000a+10000b+1000c+100a+10b+c)÷1001`
`=[(100000a+100a)+(10000b+10b)+(1000c+c)]÷1001`
`=(100100a+10010b+1001c)÷1001`
Vì `100100a÷1001=100a`
`10010b÷1001=10b`
`1001c÷1001=c`
`=>(100000a+10000b+1000c+100a+10b+c)÷1001`
`=100100a÷1001×10010b÷1001+1001c÷1001`
`=100a+10b+c`
`=bar(abc)`
`=>bar(abcabc)÷1001=bar(abc)`
Vậy `B÷1001=A`
CHÚC BẠN HỌC TỐT!!!
