abcabc: abc= abcx1001: abc= abc
abcabc : abc
= 100000a + 10000b + 1000c + 100a + 10b + c : 100a + 10b + c
= 111111 ( a + b + c ) : 111 ( a + b + c )
= 1001
rõ ràng hơn nà:
abcabc: abc= abc000+abc
abcabc = abc x1000 + abc x1
abcabc =abc x( 1000+1 )
abcbac = abc x 1001
suy ra abcabc: abc = 1001
Vậy abcbac: abc = 1001