We know that, a number is divisible by 11 when the difference between the sum of its digits at even places and sum of its digits is either 0 or the difference is divisible by 11. From option (a), Given number is 16324. ∴ Sum of digits at odd places =6+2=8 Required difference =8−8=0 Hence, the number is divisible by 11. Now, we check divisibility by 7. 1632−(2×4)=1624 162−(2×4)=154 15−(2×4)=7 Hence, 16324 is divisible by both 11 and 7.