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#57 Prime jumps
set by Christopher Dearlove
If we start with 21 (which isn’t a prime number), how many times do we have to add 100 before we reach a prime number?
Which numbers below 100 can never be made to reach a prime number by adding multiples of 100?
Returning to the case of 21: one other non-prime below 100 needs the same multiple of 100 added to it to reach a prime. What is it?
Solution next week
#56 Square sums by four
Solution
The first number is 7, for which 12 + 22 + … + 72…
