Let D be a recurring decimal of the form D=0. a1a2a1a2a1a2............; where digits a1 and a2 lie between 0 and 9. Further, at most one of them is zero. Which of the following numbers necessarily produces an integer, when multiplied by D? (CAT 2000)
D=0. a1a2 (recurring);100 D=a1a2.a1a2 (recurring). Thus, 99D=a1a2⇒D=(a1a299).
Required number should thus be a multiple of 99. Hence 198 is the required number.