Math exercises in the first volume of grade two

2、7 A 6

+ B 4 9

d 2 C

A=( ) B=( ) C=( ) D =()

There are six numbers in a row. Their average is 27, the average of the first four numbers is 24, the average of the last three numbers is 3 1, and the fourth number is ().

4. On a straight line, point A is 20mm to the left of point B, point C is 50mm to the left of point D, and point D is 40mm to the right of point B ... The order of these four points from left to right is ().

Grandpa keeps a flock of ducks. The number of ducks is 10-40.

A number between, which is a multiple of 5 and a multiple of 7. There are () ducks in this group.

6. This year, the father is four times as old as his daughter. Three years ago, my father and daughter were 39. This year, my father is () and my daughter is ().

7, Xiaohua swimming, the first swim is 25 meters, and the distance of the second swim is 8 meters more than the average distance of the two swims.

9. Xiaohong has a bundle of pencils. She first gave half to her brother, then one, and then gave the remaining half to her sister. Finally, she had only one pencil left. Xiaohong has a pencil.

10, cut a rope into four sections at least () times.

1 1、(200+ 198+ 196+……+2)-( 1+3+5+……+ 199)=( )

12, seven years ago, my mother was six times older than my son. My son is 12 years old and my mother is () years old.

13, find the rules for filling numbers: 1, 6,31,(), 78 1.

14. Plant trees beside the swimming pool with a length of 18m and a width of 12m. Plant a tree every 2 meters. * * * You can plant () trees.

15, Qingqing and Mingming * * * have 34 stamps. Obviously, after giving Qingqing 13 stamps, the number of stamps of the two people is equal. Qingqing originally had fewer stamps than Mingming.

16. There are 6 chickens and rabbits in a cage, and a cage has 20 legs. There are () chickens and () rabbits.

Second, answer the question.

1, calculated by a simple method.

22×44+22×44+22×6+22×6

( 1 1× 10×9…×3×2× 1)÷(22×24×25×27)

2. Fill in the figures according to the rules:

( 1)3,4,7, 12, 19,28,( ),( )

(2)( ),( ), 10,5, 12,6, 14,7

(3) 15,2 1, 18, 19,2 1, 17,( ),( )

3. With a platform scale, it can only weigh more than 30 kilograms, and the weights of A, B and C are all between15 and 29 kilograms. How do I weigh these three things with this scale?

4. Mother squirrel picks 20 pine nuts every day in sunny days and 12 in rainy days. It picks 1 12 pine nuts for several days, and picks 14 pine nuts every day on average. How many days does it rain these days?

5. Fill the nine numbers 3, 4, 5, 6, 7, 8, 9, 10,1in the box below, so that the sum of the three numbers in each row, column and diagonal is equal.

5. Both Party A and Party B do a three-digit plus two-digit problem. The result of Party A is 137, and that of Party B is 245. After checking, I found that B did something wrong. B add the hundredth digit of three digits with the tenth digit of two digits; Add the tenth digit of three digits with the second digit. What are the first two numbers?

6. There are 15 children playing the game of "the eagle catches the chicken", and 9 people have been caught. How many more people will be arrested?

7. 12. Write the six numbers 1, 2, 3, 4, 5, 6 on the six sides of the cube, and judge which numbers are written on the opposite side from the following three different arrangements.

( )——( ) ( )——( )

( )——( )

8. Three classes in Grade Two participated in tree planting activities and planted 50 trees. Class One, Class Two planted 38 trees, and Class Two, Class Three planted 32 trees. How many trees were planted in the three classes?

9. When the sports meeting entered the stadium, the whole class just lined up in six equal rows. Xiao Lin is in the second row. From the beginning, she stands in the fifth position, and from the back, she stands in the third position. How many people are there in this class?

10, an adult chorus of * * * 30 people, with an average age of 40 years, of which 10 has an average age of 50 years for men and an average age of women.

1 1. The student asked how old Mr. Xin was this year. Mr. Xin said, "Add 6 to my age, divide it by 2, subtract 5 and multiply it by 4, and I will be 44 years old." Do you know how old Mr. Xin is this year?

2、7 A 6

+ B 4 9

d 2 C

A=(8 ) B=(4 ) C=(5 ) D =( 1)

6+9= 15 gives D=5.

A+4+ 1=？ 3 gives A=8.

7+B+ 1=？ 2 gives B=4.

Finally D= 1

There are six numbers in a row. Their average is 27, the average of the first four numbers is 24, the average of the last three numbers is 3 1, and the fourth number is (27).

Let these six numbers be a, b, c, d, e and f.

a+b+c+d+e+f=27*6

a+b+c+d=24*4

d+e+f=3 1*3

Then (A+B+C+D)+(D+E+F)-(A+B+C+D+E+F) = D = 27.

According to the meaning of the question, draw point B first, then point A, then point D, and finally point C. You can see the order by drawing it yourself.

Grandpa keeps a flock of ducks. The number of ducks is 10-40.

Numbers between are multiples of 5 and multiples of 7. There are (35) ducks in this group.

In 10-40, only 5*7=35 is a multiple of 5 and 7.

6. This year, the father is four times as old as his daughter. Three years ago, my father and daughter were 39. This year, my father is 36 years old and my daughter is 9 years old.

Suppose the father is X and the daughter is Y.

x=4y

(x-3)+(y-3)=39 Solve the equation.

7. Xiaohua swam. The first time I swam 25 meters, the second time I swam 8 meters more than the average distance of the two tours, and the second time I swam (4 1) meters.

Let the second swim be x meters, [(25+x)/2]+8=x, and solve the equation.

9. Xiaohong has a bundle of pencils. She first gave half to her brother, then one, and then gave the remaining half to her sister. Finally, she had only one pencil left. Xiaohong has (10) pencils.

Let the original X branch, [(x/2)-1]/2-1=1,solve the equation.

10, cut a rope into four sections at least (2) times.

If you want to divide it into four parts, fold it in half and then fold it in half, and then cut a knife in each of the two folded places.

1 1、(200+ 198+ 196+……+2)-( 1+3+5+……+ 199)=( 100 )

200-1 99+198-197 ...+2-1,and each subtraction is equal to1,* * 100 times, which adds up to/kloc-0.

12, seven years ago, my mother was six times older than my son. My son is 12 years old and my mother is (37) years old.

Let the mother be x years old and x-7=( 12-7)*6.

13, find the rules for filling numbers: 1, 6,31,(156), 78 1.

The difference between 1 and 6 is 5, 6 and 31; 25 = 5 * 5, the difference between 3 1 and 156 is 125 = 5 * 5, 156 and 78 1 is 625 = 5 * 5.

14. Plant trees beside the swimming pool with a length of 18m and a width of 12m. Plant a tree every 2m, and * * * can plant (30) trees.

One side of18m can be planted 10, 20 plants on both sides, 7 plants on one side of12m, and 4 plants on both sides of 14. Excluding the four-point repeat value of 4, * * 30 plants.

15, Qingqing and Mingming * * * have 34 stamps. Obviously, after giving Qingqing 13 stamps, the number of stamps of the two people is equal. Qingqing originally had 26 fewer stamps than Mingming.

x- 13=y+ 13

16. There are 6 chickens and rabbits in a cage, and a cage has 20 legs. There are (2) chickens and (4) rabbits.

solve an equation

x+y=6

2*x+4*y=20

Second, answer the question.

1, calculated by a simple method.

22×44+22×44+22×6+22×6 =22(44+44+6+6)=2200

2. Fill in the figures according to the rules:

( 1)3,4,7, 12, 19,28,(39 ),(52 )

The difference between each number is 1, 3, 5, 7, 9, 1 1, 13.

(2)(8 ),(4 ), 10,5, 12,6, 14,7

The former number is twice that of the latter, and the difference of the latter number is 1.

(3) 15,2 1, 18, 19,2 1, 17,( ),( )

3. With a platform scale, it can only weigh more than 30 kilograms, and the weights of A, B and C are all between15 and 29 kilograms. How do I weigh these three things with this scale?

Let A+B =a+C =b+C =c to solve the equation.

A =(a+b-c)/2

B =(a-b+c)/2

C =(c-a+b)/2

Let it be sunny for x days and rainy for y days.

Solve equation 20x+12y =112.

(x+y)* 14= 1 12

2 sunny days, 6 rainy days.

5. Fill the nine numbers 3, 4, 5, 6, 7, 8, 9, 10,1in the box below, so that the sum of the three numbers in each row, column and diagonal is equal.

4 9 8

1 1 7 3

6 5 10