Answer:
1, 4 or 7
Step-by-step explanation:
The divisibility rule/shortcut for 3 is that the sum of its digits is divisible by 3. So, you currently have 29 (7+1+7+6+2+6+0), and you have to make that number divisible by 3.
adding 1 gets you 30, which we know is divisible by 3.
then, instead of trying every digit, we can note that
30 , 33 , 36 , 39 ....
are divisible by 3.
But the most we can add to the sum of 29 is 9 (because that is the highest digit possible)--so numbers above 38 are irrelevant
so, we want to find out if we can make 29 into 30, 33, or 36
adding 1 to 29 = 30
adding 4 to 29 = 33
adding 7 to 29 = 36
So, by making the first digit 1 , 4 , or 7, you make the number divisible by 3 (making the sentence true)
