Speed ​​calculation, reserve education kid afterwa

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, complementary tail (tail amount equal to 10):
formulas: a first add 1 to the head by head,Air Max, 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, the same as dissimilar multiplier:
formulas: a 1st increase 1 to the pate at pate, tail by tail.
Example: 37 × 44 =?
solution: 3 +1 = 4
4 × 4 = 16
7 × 4 = 28
; 37 × 44 = 1628
Note: a bit amplify, no to use the 0 numeral placeholder.

4. dozens of dozens of one by one:
formulas: the head by head,Men's Air Max 2009, head plus head, tail by tail.
Example: 21 × 41 =?
solution: 2 × 4 = 8
2 +4 = 6
1 × 1 = 1
; 21 × 41 = 861

5.11 by anybody number:
formulas: the whereabouts of the nailed end to end, in the navel of the drop-down.
Example: 11 × 23125 =?
solution: 2 +3 = 5
3 +1 = 4
1 +2 = 3
; 2 +5 = 7
2 and 5,Men's Air Max 95, respectively,Air Max 180, in the beginning and end
11 × 23125 = 254375
Note: and over 10 to enter an.

6. dozen by any number:
formulas: Second Take the first namely not the whereabouts of several trends,Nike Air Max, the first factor of the second digit is multiplied by a ingredient behind each number, plus the next digit,AirMax Shoes, another 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.