Answer:
DOG = 270
Explanation:
270 × 3 = 810
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The only numbers that end in the same digit when multiplied by 3 are 0 and 5.
0×3 = 0
5×3 = 15
If G is 5, then you are looking for digits DO than give a product of 80 when multiplied by 3. 80 is not divisible by 3, so that doesn't work.
G must be 0.
Then the product of DO and 3 is 81, so DO = 81/3 = 27.
The solution is ...
D = 2
O = 7
G = 0