Greatest three digit number = 999
To find the divisible number, LCM of three number is require,
Factors of 12 = 3 × 4 = 22 × 3
Factors of 30 = 6 × 5 = 2 × 3 × 5
Factors of 50 = 25 × 2 = 2 × 52
LCM of (12, 30, 50) = 22 × 3 × 52 = 300
On dividing 999 by 300, the remainder 99,
∴ Largest divisible number = 999 – 99 = 900.