Question

What least number should be subtracted from $26492518$ so that the resulting number is divisible by $3$ but not by $9?$

Answer 1

Since as we know that according to the divisibility test sum of all digits of number divisible by $3$and $9$ then the number is also divisible by $3$and $9$ .

$26492518$ is $2+6+4+9+2+5+1+8=37.$

If $1$is subtracted from $26492518$ then sum of all digits is $36$ which is divisible by $3$and $9$ both.

If $4$ is subtracted from $26492518$ then sum of all digits is $33$ which is divisible by $3$ not by $9.$

Hence, $4$ should be subtracted from $26492518$ so that the resulting number is divisible by $3$ but not by $9.$