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0
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A  is an integer that reads the same forwards and backwards. How many positive 3-digit palindromes are multiples of 3?

 Sep 2, 2020
 #2
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+1

(111, 141, 171, 222, 252, 282, 303, 333, 363, 393, 414, 444, 474, 525, 555, 585, 606, 636, 666, 696, 717, 747, 777, 828, 858, 888, 909, 939, 969, 999) >>Total = 30 such numbers

 Sep 2, 2020
 #3
avatar+110835 
+2

9 with all three digits the same

 

9*9*1=81 ways to choose a two different digit ones.

[The first and last number can be 1,2,3,4,5,6,7,8,9        9 choices

the middle number can be any number, including 0 but not including the number already chosen  9 choices]

 

So I get 90 ways.

 Sep 2, 2020
 #4
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+1

Hi Melody: They have to be "Multiples of 3".

Guest Sep 2, 2020
 #5
avatar+110835 
+1

ok thanks, I didn't see that.

 

 

11 with 1,4,7

22 with 2,5,8

33 with 0,3,6,9

10 possibilities

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44 with 1,4,7

55

66

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77

88

99

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3*10 = 30 possibilities

 

Just like you already said.       cool

Melody  Sep 2, 2020

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