Some positive integers n have the property that the sum
[ n + reverse(n) ] consists entirely of odd (decimal) digits.
For instance, 36 + 63 = 99 and 409 + 904 = 1313.
We will call such numbers reversible; so 36, 63, 409, and 904 are reversible. Leading zeroes are not allowed in either n or reverse(n).
There are 120 reversible numbers below one-thousand.
a. Evaluate how many reversible numbers are there
below 10k, k=2,3... up to 6 or 7 .
b. Analyze the results, aiming to find the relation (i.e. approximate function) between N(k) and k.
Source: Project Euler, modified.
(In reply to
re: part a computer solution wrong? by Ady TZIDON)
I find this lack of acceptance unacceptable.
Here are the first 40 7-digit numbers, their reverses and the sums:
2020909 9090202 11111111
2020929 9290202 11311131
2020949 9490202 11511151
2020969 9690202 11711171
2020989 9890202 11911191
2021909 9091202 11113111
2021929 9291202 11313131
2021949 9491202 11513151
2021969 9691202 11713171
2021989 9891202 11913191
2022909 9092202 11115111
2022929 9292202 11315131
2022949 9492202 11515151
2022969 9692202 11715171
2022989 9892202 11915191
2023909 9093202 11117111
2023929 9293202 11317131
2023949 9493202 11517151
2023969 9693202 11717171
2023989 9893202 11917191
2024909 9094202 11119111
2024929 9294202 11319131
2024949 9494202 11519151
2024969 9694202 11719171
2024989 9894202 11919191
2030809 9080302 11111111
2030829 9280302 11311131
2030849 9480302 11511151
2030869 9680302 11711171
2030889 9880302 11911191
2031809 9081302 11113111
2031829 9281302 11313131
2031849 9481302 11513151
2031869 9681302 11713171
2031889 9881302 11913191
2032809 9082302 11115111
2032829 9282302 11315131
2032849 9482302 11515151
2032869 9682302 11715171
2032889 9882302 11915191
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Posted by Charlie
on 2015-08-07 22:27:09 |
re(2): part a computer solution wrong?
