 Wysłany: Pon 7:30, 06 Gru 2010 Temat postu: Speed calculation, taught his son to keep the futu |
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| 1. ten by ten:
formulas: the head by head, tail plus tail, tail by tail. Example: 12 × 14 =? solution: 1 × 1 = 1 2 +4 = 6 2 × 4 = 8 12 × 14 = 168 Note: a bit multiply, not use the 0 digit placeholder. 2. head the same, complementary tail (tail add up to 10): formulas: a first add 1 to the head by head, tail by tail. Example: 23 × 27 =? Solution: 2 +1 = 3 2 × 3 = 6 3 × 7 = 21 23 × 27 = 621 Note: a bit multiply,coach handbag outlet store, not use the 0 digit placeholder. 3. complementary first multiplier,imitation coach handbags, the same as the other multiplier: formulas: a first add 1 to the head by head,buy coach handbags, tail by tail. Example: 37 × 44 =? solution: 3 +1 = 4 4 × 4 = 16 7 × 4 = 28 ; 37 × 44 = 1628 Note: a bit multiply, not use the 0 digit placeholder. 4. dozens of dozens of one by one: formulas: head by head,monster beats headphones, head plus head, tail by tail. Example: 21 × 41 =? solutions: 2 × 4 = 8 2 +4 = 6 1 × 1 = 1 ; 21 × 41 = 861 5.11 by any number: formulas: sum of fixed fate, and the middle of the drop-down. Example: 11 × 23125 =? Solution: 2 +3 = 5 3 +1 = 4 1 +2 = 3 ; 2 +5 = 7 2 and 5, respectively, in the sum of 11 × 23125 = 254375 Note: and over ten to get into one. 6. dozen by any number: formulas: Second Take is not the first fate of several trends, the first digit multiplied by the factor behind the second factor of each number,tory burch sale, plus the next digit, again missing. Example: 13 × 326 =? solution: 13 bits is 3 3 × 3 +2 = 11 3 × 2 +6 = 12 ; 3 × 6 = 18 13 × 326 = 4238 Note: and over ten to get into one. |
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