12345679 × 9 = 11111112345679 × 18 = 222222, what law do you find

12345679 × 9 = 11111112345679 × 18 = 222222, what law do you find


The result of multiplying 12345679 by a multiple of nine is the number of multiples of nine



123456789+987654321+111111111+222222222+333333333+444444444+555555555+666666666=
problem in arithmetic