Question

Write the smallest digit in the blank space for the given number so that the number formed is divisibly by 3:
__6724

Answer 1

We know that a number is divisible by 3 if the sum of all digits is divisible by 3.
If we put 2 in the blank the sum of the digits become:
$\underset{–}{2}6724=2+6+7+2+4=21$
Now, 21 is divisible by 3.
Hence, the smallest digit in the blank space is 2.