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Reprinted from 1409968101 at 08:22 on July 1st, 2010 Read (loading. ..) Comments (0) Category: Personal Diary
1. ten by ten:
formulas: the head by head,
red wing heritage boots, tail plus tail,
red wing shoe store, 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,
red wing shoes outlet, tail by tail.
Example: 23 × 27 =?
Solution: 2 +1 = 3
2 × 3 = 6
3 × 7 = 21
23 × 27 = 621
Note: a bit multiply, not use the 0 digit placeholder.
3. complementary first multiplier, the same as the other multiplier:
formulas: a first add 1 to the head by head, tail by tail.
Example: 37 × 44 =?
solution: 3 +1 = 4
4 × 4 = 16
7 × 4 = 28
; 37 × 44 = 1628
Note: a bit multiply,
red wing motorcycle boots, not use the 0 digit placeholder.
4. dozens of dozens of one by one:
formulas: head by head, 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,
red wing boots, 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,
red wing shoes, 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.
labels fast calculation formulas multiplier digit digit