ab x 101 = ab x ( 100 + 1 )
= ab x 100 + ab x 1
= ab00 + ab
= abab
b ) abc x 7 x 11 x 13 = abc x 1001
abc x ( 1000 + 1 )
= abc x 1000 + ab x 1
= abc000 + abc = abcabc
ab x 101 = ab x ( 100 + 1 )
= ab x 100 + ab x 1
= ab00 + ab
= abab
b ) abc x 7 x 11 x 13 = abc x 1001
abc x ( 1000 + 1 )
= abc x 1000 + ab x 1
= abc000 + abc = abcabc