Speed ​​calculation, reserve education kid the fu
 

1. More than 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 morsel multiply, not use the 0 digit placeholder.
2. brain the same, complementary tail (tail join up apt 10):
formulas: a first add 1 to the head by head,Lacoste Zepher MR2 Trainers, tail by tail.
Example: 23 × 27 =?
Solution: 2 +1 = 3
2 × 3 = 6
3 × 7 = 21
23 × 27 = 621
Note: a bit multiply,Lacoste Swerve Keyline Trainers, not use the 0 digit placeholder.
3. complementary first multiplier, the same for the additional multiplier:
formulas: a first add 1 to the head by head,Lacoste Finham SPM Trainers, 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, 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: amount of nailed destiny,Lacoste Carnaby Trainers, 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,Lacoste Camden Trainers, in the end to end
11 × 23125 = 254375
Note: and over ten to get into one.
6. dozen by any number:
formulas: the whereabouts of the second movement is not the first multiplier,Lacoste Shoes, the first numeral multiplied by the element The second factor backward each digit, and the next number, repeatedly 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.