A well-known rule used to find the square of an integer with decimal expansion (anan−1 … a1a0)10 and final digit a0 = 5 is to find the decimal expansion of the product (anan−1 … a1)10 [(anan−1 … a1)10 + 1], and append this with the digits (25)10. For instance, we see that the decimal expansion of (165)2 begins with 16 · 17= 272, so that (165)2 = 27,225. Show that this rule is valid.
We need at least 10 more requests to produce the solution.
0 / 10 have requested this problem solution
The more requests, the faster the answer.