Too much bad, keep teaching children after
 

1. ten by ten:
formulas: the head by head, tail plus tail,herve leger bandage dress, tail by tail.
Example: 12 × 14 =?
solution: 1 × 1 = 1
2 +4 = 6
2 × 4 = 8
12 × 14 = 168
Note: a bit multiply,ed hardy shirts, not use the 0 digit placeholder.

2. head the same,juicy couture velour, 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, not use the 0 digit placeholder.

3. complementary first multiplier,cheap silver jewelry, 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, not use the 0 digit placeholder.

4. dozens of dozens of one by one:
formulas: head by head,paul smith cufflinks, 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,juicy couture pas cher, 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, 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.