"pro mac cosmetics " 6 kinds of speed calculation
 

1. dozen by dozen:
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 to use the 0 digit placeholder.

2. head the same,"tory burch mini bag " Classic comedy masterpiece campus couplet !, complementary tail (tail sum equal to 10):
formulas: a first add 1 to the head by head,"pro mac cosmetics ", 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. the first multiplier complementary,"tory burch 2011 " Enhance the intelligence of the baby 40 s,"sunglasses paul smith ", the same as another 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, not to use the 0 digit placeholder.

4. dozens of dozens of one by one:
formulas: the head by head, head plus head,"tory burch wedge thora ", tail by tail.
Example: 21 × 41 =?
solution: 2 × 4 = 8
2 +4 = 6
1 × 1 = 1
; 21 × 41 = 861

5.11 by any number:
formulas: the whereabouts of the fixed end to end, in 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 beginning and end
11 × 23125 = 254375
Note: and over 10 to enter one.

6. dozen by any number:
formulas: Second Take the first is not the whereabouts of several trends,"salvatore ferragamo wristlet ", the first factor of the second digit is multiplied by a factor behind each number, plus the next digit,"uk abercrombie and fitch " 2010-12-8,"tory burch black flats ", again falling.
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 10 to enter one.