How many ways are there to arrange the numbers 0-9 inclusive in a line such that each digit is a either a divisor of both of its neighbors or an integer multiple of both of its neighbors? (Ex: …248… would not work as 8 is not a divisor of 4 and 2 is not an integer multiple of 4, but …426… would work as 2 is a divisor of both) Note: 0 does not count as a divisor
MathForAll
How many ways are there to arrange the numbers 0-9 inclusive in a line such that each digit is a either a divisor of both of its neighbors or an integer multiple of both of its neighbors? (Ex: …248… would not work as 8 is not a divisor of 4 and 2 is not an integer multiple of 4, but …426… would work as 2 is a divisor of both)
Note: 0 does not count as a divisor
1 year ago | [YT] | 1
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MathForAll
What is the last digit of 2^100?
HINT:
Consider the Chinese Remainder Theorem… How can we get the last digit using mods?
#NumberTheory #QuantPrep #QuantInterview
1 year ago | [YT] | 1
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