Medium
378___90 - Which of the following digits should be filled in the blank so that the number is divisible by 9?
Explanation
Explanation
For a number to be divisible by 9, the sum of its digits must be a multiple of 9. Adding the known digits: 3+7+8+9+0 = 27, which is already a multiple of 9. So the missing digit must be 9 (making the new sum 27+9=36, still a multiple of 9); 0 would also work but is not among the options.
PRO TIP
Re-check your working by substituting the answer back into the original question.