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Robust numbers (Posted on 2024-06-02) Difficulty: 3 of 5
An eight-digit number is said to be 'robust' if it meets both of the following conditions:

(i) None of its digits is 0.
(ii) The difference between two consecutive digits is 4 or 5.

Answer the following questions:

(a) How many robust numbers are there?
(b) A robust number is said to be 'super robust' if all of its digits are distinct. Calculate the sum of all the super robust numbers.

No Solution Yet Submitted by Danish Ahmed Khan    
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  Subject Author Date
Puzzle ThoughtsK Sengupta2024-06-02 22:28:31
SolutionSolution: Analytical with Computer confirmationLarry2024-06-02 13:18:30
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