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We call a number sticky if every digit in the number is either a 3 or next to a 3 For example, the numbers  333,83,303  and 3773  are all sticky, but the numbers 32523, 786, 340,   and 3999 are not sticky.

How many positive 2-digit numbers are sticky?

 Feb 4, 2020
 #1
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There are 10 two-digit numbers with a tens digit of 3, and 10 two-digit numbers with a units digit of 3, so the answer is 10 + 10 = 20.

 Feb 4, 2020
 #2
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Just list them!
13, 23, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 43, 53, 63, 73, 83, 93 =18 such NUMBERS or INTEGERS.

 Feb 4, 2020

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