1. 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,
GHD NZ, no use the 0 digit placeholder.
2. head the same, complementary tail (tail add up to 10):
formulas: a premier multiplication 1 to the brain along 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, the same as the other multiplier:
formulas: a first add 1 to the head by head,
GHD Blue Butterfly 2011, tail by tail.
Example: 37 × 44 =?
solution: 3 +1 = 4
4 × 4 = 16
7 × 4 = 28
; 37 × 44 = 1628
Note: a bit multiply,
GHD MK4 Gold Straighteners, not use the 0 digit placeholder.
4. dozens of dozens of an by one:
formulas: head by head, head and head,
GHD Purple Straighteners, 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 fixed destiny,
GHD Green Butterfly 2011, and 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,
GHD Leopard Grain, respectively, in the sum of
11 × 23125 = 254375
Note: and over ten to get into one.
6. dozen by anyone number:
formulas: Second Take is not the first fate of several trends, the first digit multiplied by the element after the second ingredient of every digit, plus the next digit, anew missing.
Example: 13 × 326 =?
solution: 13 bits namely 3
3 × 3 +2 = 11
3 × 2 +6 = 12
; 3 × 6 = 18
13 × 326 = 4238
Note: and over ten to get into one.
Speed calculation, behind education kid keep
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