Question

Using divisibility test, determine which of the following numbers are divisible by 11:

(a) 5445 

(b) 10824 

(c) 7138965 

(d) 70169308

Answer 1

(a) 5445 --> Sum of the digits at odd places = 4 + 5 = 9

--> Sum of the digits at even places = 4 + 5 = 9

--> Difference of both sums = 9 – 9 = 0

(b) 10824 --> Sum of the digits at odd places = 4 + 8 +1 = 13

--> Sum of the digits at even places = 2 + 0 = 2

--> Difference of both sums = 13 – 2 = 11

(c) 7138965 --> Sum of the digits at odd places = 5 + 9 + 3 + 7 = 24

-->Sum of the digits at even places = 6 + 8 + 1 = 15

--> Difference of both sums = 24 – 15 = 9

Since the difference is neither 0 nor 11, therefore, the number is not divisible by 11.

(d) 70169308 --> Sum of the digits at odd places = 8 + 3 + 6 + 0 = 17