Question 974852: Still don't understand
The 14 digits of a credit card are written in the boxes shown. If the sum of any three consecutive digits is 16, what is the value of A? A _ 4 _ _ _ _ _ _ _ _ 4 _ 9
Answer by htmentor(1343)   (Show Source):
You can put this solution on YOUR website! The 14 digits of a credit card are written in the boxes shown.
If the sum of any three consecutive digits is 16, what is the value of A?
A _ 4 _ _ _ _ _ _ _ _ 4 _ 9
Since any three consecutive digits (in other words, 3 in a row) must add up to 16, start with the last three numbers.
We have 4 + 'blank' + 9 = 16, so the number in the blank must be 3.
Now we work backwards from there. We have blank + 3 + 4 = 16, so 'blank' must be 9.
If we keep working backwards, we see that the pattern 439 repeats. So the digits are A_439439439439, which means 'blank' must be 9 and therefore A=3
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