Ask math questions 2 4 6 8 18 20 in the easiest way

2+4+6+8...18+20, it is easy to see that the sum of the 1st number plus the 10th number, the sum of the 2nd number and the 9th number ,..., the sum of the 5th number plus the 6th number is 22, so the sum = 22 5 = 110.

The role of simple calculations:1. Simple calculation enables students to quickly and accurately calculate the correct answer in a short period of time.

2. Simple operation and four mixed operations.

It does not operate in the order of four mixed operations, but uses various operation properties and laws of operation to carry out operations, which is a special way of operation.

3. There are many types of "simple operation" questions, which can generally be divided into two categories: "law of operation" and "nature of operation" for operation.

4. The use of simple calculation methods in mathematics can greatly save the time of doing problems.

The first is. 2+20）x5=110

Teachers should have taught before.

1+2+3+4……+10=(1+10)x(10 2)=55, which is the first number plus the last number and then multiplied by half of the number of numbers, in fact, it is a truth).

The second way is actually the same truth, which can be seen as this.

2+4+6+……20）-（1+3+5+7+……19）=（2+20）x5-（1+19）x5=（22-20）x5=10

Add the first term and the last term in the above equation, i.e., 2+20=22, and finally 10+12=22

So there are 5 such additions, so 2+4+6+8....18+20=5x（2+20)=110

Note that 20-19 = 1 is observed

Finally, 2-1=1

There are 10 such equations in this equation, so it is equal to the addition of 10 1s = 10

(1) 2+4+6+8...18+20, it is easy to see that the sum of the 1st number plus the 10th number, the sum of the 2nd number and the 9th number ,..., the sum of the 5th number plus the 6th number is 22, so the sum = 22 5 = 110.

The first is (2+20)x5=110

Teachers should have taught before.

1+2+3+4……+10=(1+10)x(10 2)=55, which is the first number plus the last number and then multiplied by half of the number of numbers, in fact, it is a truth).

The second way is actually the same truth, which can be seen as this.

2+4+6+……20）-（1+3+5+7+……19）=（2+20）x5-（1+19）x5=（22-20）x5=10

2+4+6+8...18+20

Add the first term to the last term in the above equation, i.e., 2+20=224+18=22

Finally, it is 10 + 12 = 22

So there are 5 such additions, so 2+4+6+8....18+20=5x（2+20)=110

20-19+18-17+16-15...4-3+2-1 Note observed 20-19=1

Finally, 2-1=1

There are 10 such equations in this equation, so it is equal to the addition of 10 1s = 10

Removing -2 and 20 has a total of 4 pairs of 4+18, 6 plus 16, 8 plus 14, 10+12, 22*4=88, then 88-2+20=106

(Prime Minister plus tail phase) multiply by the number of phases divided by 2 Try it should work.

1024+512+256...2+1+1/2+1/4+1/8+..1/512+1/1024 =2^ 10+2^ 9+2^ 8...

2^ 1+2^ 0+2^ (1)+2^ (2)+2^ (3)+.2 (9)+2 (10) This is a sum of proportional sequences, q=1 2, the number of terms is 11, sn=a1(1-q n) (1-q)=(a1-an*q) (1-q) 2 10+2 9+2 8....2^ 1+2^ 0+2^ (1)+2^ (2)+2^ (3)+.

2 (9)+2 (10) =2 10-2 (10)*(1 2)] 1-1 2) =2 11-2 (10) =2047 and 1023 1024