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avatar+809 

How many two-digit numbers have digits which add up to 7?

 

16

25

34

43

52

61

70

 

So, 7, right?

 Dec 4, 2018
 #1
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0

That is what I get!.

 Dec 4, 2018
 #2
avatar+601 
0

We have eight pairs.

{0, 7} {1, 6}{2, 5} {3, 4} {4, 3} {5, 2} {6, 1} {7, 0}

However, {0, 7} doesn't work because 7 is just a one digit number, so we have \(8-1=7\) total possibilities. You were right!

 

You are very welcome!

:P

 Dec 5, 2018

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