LCM of 5, 6, 8, 9 and 12 = 360. Hence, the smallest number which when divided by 5, 6, 8, 9 and 12 leaves 1 as remainder in each case will be 360 + 1 = 361. But 361 is not completely divisible by 13. Hence, on considering 360 × 2 + 1, 360 × 3 + 1,... , 360 × n + 1, we conclude that 360 × 10 + 1 = 3601 is the required number.