According to the question, 80=10×8 Clearly, 347XY is divisible by 10. So, Y = 0. Now, 347 X 0 is divisible by 8. It means last three digits 7X 0 is divisible by 8. Hence, X = 2 or 6. If X =2, number 34720 which is divisible by 80. If X = 6, number 34760 which is not divisible by 80. ∴ X + Y = 2 + 0 = 2