Question 963831: choose a number between 55 and 101 that is a multiple of 3,6, and 7. Write all the numbers that she could choose.
Answer by fcabanski(1391)   (Show Source):
You can put this solution on YOUR website! Multiples of 7 in that range: 56, 63, 70, 77, 84, 91, 98
Check if they're multiples of 3. For multiples of three, the digits will add to a multiple of 3. 6+5=11, which isn't a multiple of 3. So 56 isn't a multiple of three:
6+3= 9, yes to 63. No to 70, 74, 91 and 98. Yes to 84: 4+8 = 12.
So now it's down to 63 and 84. Only 84 is evenly divisible by 6, so only 84 is a multiple of 6.
84 is the answer.
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