Perkalian 2 Digit Yang Angka Terakhirnya Berjumlah 10

0

11 x 19 =0 209 = (1^2 + 1)1 * 9 = (1 * 2)1 * 9

12 x 18 =0 216 = (1^2 + 1)2 * 8 = (1 * 2)2 * 8

23 x 27 =0 621 = (2^2 + 2)3 * 7 = (2 * 3)3 * 7

24 x 26 =0 624 = (2^2 + 2)4 * 6 = (2 * 3)4 * 6

35 x 35 = 1225 = (3^2 + 3)5 * 5 = (3 * 4)5 * 5

45 x 45 = 2025 = (4^2 + 4)5 * 5 = (4 * 5)5 * 5

Rumus :

ab * a(10 - b) = (a * (a + 1))b * (10 - b)