Question

A digit is written to the right of the units digit of 757. If the resulting four-digit number is divisible by 3, how many possibilities are there for the digit that was written?

Answer 1

3

Explanation:

It is a well known trick that when you add together the digits of a number, if they are a multiple of 3 then the number is divisible by 3. Let's go through the options and check them:

7+5+7+0=19 not a multiple of 3

7+5+7+1=20 not a multiple of 3

7+5+7+2=21 multiple of 3

7+5+7+3=22 not a multiple of 3

7+5+7+4=23 not a multiple of 3

7+5+7+5=24 multiple of 3

7+5+7+6=25 not a multiple of 3

7+5+7+7=26 not a multiple of 3

7+5+7+8=27 multiple of 3

7+5+7+9=28 not a multiple of 3

As you can see, only 3 of these were possibilities that satisified the conditions. Hope this helps!