SQUARES OF NUMBERS
THAT END WITH 5.
A number that ends in 5 has the form A = 10a + 5, where a has one digit less than A. To find the square A² of A, append 25 to the product a×(a + 1) of a with its successor. For example, compute 115². 115 = 11×10 + 5,so that a = 11. First compute 11×(11 + 1) = 11×12 = 132 (since 3 = 1 + 2). Next, append 25 to the right of 132 to get 13225!
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