Question

How many of the given numbers are not divisible by $11$?

• A. $4$
• B. $7$
• C. $6$
• D. $5$

Answer 1

Answer: (C)

$6$

Given Numbers are $17871,1007453,4343143,990039,125144,888888,6412$

Divisibilty test of $11$ is as follows:

Take sum of alternate digits from left and then subtract it from the sum of numbers present at even places from the left. and then check if the result is divisible by $11$.

Using this divisibility test:

$17871$ $\to$ $(1+8+1)$ $-$ $(7$+$7)$ $\to$ $-4$

$1007453$ $\to$ $(1+0+4+3)$ $-$ $(0+7+5)$ $\to$ $-4$

$4343143$ $\to$ $(4+4+1+3)$ $-$ $(3+3+4)$ $\to$ $2$

$990039$$\to$ $(9+0+3)$ $-$ $(9+0+9)$ $\to$ $-6$

$125144$ $\to$ $(1+5+4)$ $-$ $(2+1+4)$ $\to$ $3$

$888888$ $\to$ $(8+8+8)$ $-$ $(8+8+8)$ $\to$ $0$

$6412$ $\to$ $(6+1)$ $-$ $(4+2)$ $\to$ $1$

By divisibility test, only $0$ is divisible by $11$, so is $888888$