Let N1=123456789
Erase n digits and shrink the remnants of N1 into one continuous chain creating a new number N1'.

What is the minimum number of digits to be erased so that N1' will be a square number?

Same question for N2=987654321 and N2'.

(In reply to re: Solution by cheating by Charlie)

Yep,  Thanks for catching that.  Must not have ctrl-c before the second ctrl-v.

Posted by Jer on 2018-04-05 14:56:11