The formula of 19× 19 can not only improve children's mathematical operation ability, but also exercise their thinking, analysis and creativity. Children in India, a powerful country in mathematics, can recite the formula 19× 19. Therefore, they always perform well in international mathematics competitions. No one can compare with them in making computer software. Perhaps from the formula 19× 19, we can find the reason why India is strong in the field of information technology.

The specific functions of the formula 19× 19 are as follows:

First, speed up multi-digit multiplication

If it is a two-digit multiplication operation, the formula 19× 19 can be used directly. For example, to calculate 235× 19, if you are a child who only recites the multiplication formula of 99, you need to calculate 235× 10 and 235×9 respectively. Children who have memorized the formula 19× 19 can work it out in one step, but get twice the result with half the effort.

Second, the operation of addition, subtraction, multiplication and division will also magically become faster.

What is 256÷ 16? Children who only recite the multiplication formula of 1999 need to do calculations by hand. When they recite the formula of 19× 19, they can understand that the answer is 16 at the moment they see the question. Because 16× 16=256 has been firmly fixed in the brain.

Third, divisors and multiples, understanding the nature of numbers

Students in the advanced stage of primary school have learned a number with certain properties, such as divisor and multiple, which is the relationship between learning numbers. After reciting the formula 19× 19, 285= 15× 19 will immediately appear in your mind. We also understand the nature of the number 285. 285 is a multiple of 15 and 19; Conversely, there are 15 and 19 in the divisor of 285.

Fourth, the decimal operation is fast and simple.

For example, for 2/ 15 +3/ 17, the denominator 15 and the denominator 17 must be divided, and the division process includes the following calculations: 15× 17=255, 2×. We can work out the answer in no time. In the process of learning 19× 19 formula, it can also help us better understand the nature of divisor and multiple, and the calculation of fraction will become easier.

Students fully realize the value of reciting and begin to recite with great interest! In order to make children recite more easily and quickly, I have thought of many ways. Firstly, the formula is divided into two stages: 1 1× 1 to 19× 19. Practice reciting formulas at 19×9 first, and then at 19× 19. Several melodies are obviously applied. Pay and gain. After just a few classes, most children can skillfully report the number of questions in each period.

I believe that memorizing 19× 19 formula will bring unexpected gains to children's future study!

Multiplication table (19× 19 multiplication table)

The multiplication of 1 is:

1× 1= 1 1×2=2 1×3=3 1×4=4 1×5=5 1×6=6 1×7=7 1×8=8 1×9=9

1× 10= 10 1× 1 1= 1 1 1× 12= 12 1× 13= 13 / kloc-0/× 14= 14 1× 15= 15

1× 16= 16 1× 17= 17 1× 18= 18 1× 19= 19

Twice the multiplication is:

2×2=4 2×3=6 2×4=8 2×5= 10 2×6= 12 2×7= 14 2×8= 16 2×9= 18

2× 10=20 2× 1 1=22 2× 12=24 2× 13=26 2× 14=28 2× 15=30

2× 16=32 2× 17=34 2× 18=36 2× 19=38

The multiplication of 3 times is:

3×3=9 3×4= 12 3×5= 15 3×6= 18 3×7=2 1 3×8=24 3×9=27

3× 10=30 3× 1 1=33 3× 12=36 3× 13=39 3× 14=42 3× 15=45

3× 16=48 3× 17=5 1 3× 18=54 3× 19=57

The multiplication of 4 times is:

4×4= 16 4×5=20 4×6=24 4×7=28 4×8=32 4×9=36

4× 10=40 4× 1 1=44 4× 12=48 4× 13=52 4× 14=56 4× 15=60

4× 16=64 4× 17=68 4× 18=72 4× 19=76

The multiplication operation of 5 times is:

5×5=25 5×6=30 5×7=35 5×8=40 5×9=45

5× 10=50 5× 1 1=55 5× 12=60 5× 13=65 5× 14=70 5× 15=75

5× 16=80 5× 17=85 5× 18=90 5× 19=95

The multiplication operation of 6 times is:

6×6=36 6×7=42 6×8=48 6×9=54

6× 10=60 6× 1 1=66 6× 12=72 6× 13=78 6× 14=84 6× 15=90

6× 16=96 6× 17= 102 6× 18= 108 6× 19= 1 14

The multiplication operation of 7 times is:

7×7=49 7×8=56 7×9=63 7× 10=70

7× 1 1=77 7× 12=84 7× 13=9 1 7× 14=98 7× 15= 105

7× 16= 1 12 7× 17= 1 19 7× 18= 126 7× 19= 133

Eight times the multiplication is:

8×8=64 8×9=72 8× 10=80

8× 1 1=88 8× 12=96 8× 13= 104 8× 14= 1 12 8× 15= 120

8× 16= 128 8× 17= 136 8× 18= 144 8× 19= 152

The multiplication operation of 9 times is:

9×9=8 1 9× 10=90

9× 1 1=99 9× 12= 108 9× 13= 1 17 9× 14= 126 9× 15= 135

9× 16= 144 9× 17= 153 9× 18= 162 9× 19= 17 1

10 is multiplied by:

10× 10= 100 10× 1 1= 1 10 10× 12= 120 10× 13= 130 10× 14= 140

10× 15= 150 10× 16= 160 10× 17= 170 10× 18= 180 10× 19= 190

1 1 is multiplied as follows:

1 1× 1 1= 12 1 1 1× 12= 132 1 1× 13= 143 1 1× 14= 154 1 1× 15= 165

1 1× 16= 176 1 1× 17= 187 1 1× 18= 198 1 1× 19=209

12 is multiplied by:

12× 12= 144 12× 13= 156 12× 14= 168 12× 15= 180

12× 16= 192 12× 17=204 12× 18=2 16 12× 19=228

13 is multiplied by:

13× 13= 169 13× 14= 182 13× 15= 195

13× 16=208 13× 17=22 1 13× 18=234 13× 19=247

14 is multiplied by:

14× 14= 196 14× 15=2 10 14× 16=224

14× 17=238 14× 18=252 14× 19=266

15 is multiplied by:

15× 15=225 15× 16=240 15× 17=255 15× 18=270 15× 19=285

16 is multiplied by:

16× 16=256 16× 17=272 16× 18=288 16× 19=304

17 is multiplied by:

17× 17=289 17× 18=306 17× 19=323

18 is multiplied by:

18× 18=324 18× 19=342

19 is multiplied by:

19× 19=36 1