Asking for leave is not only an adjustment period to continue learning new knowledge, but also a "rescue period" to make up for the vacancy and an "extraordinary period" to consolidate and improve. So students must finish their summer homework carefully. Now I have sorted out 20 15, and the answer is for reference only. Everyone must do it independently!

20 15

First, please fill in:

1, a box of chocolates * * * has 15, which is distributed to three students on average. Each bar of chocolate is 15 1 of this box of chocolates, and everyone's chocolate share is 3 15 of this box of chocolates.

2, 3 meters long rope cut into 5 equal parts, each part is 1, 5 this rope, each part is 3 meters long.

Distribute 5 kilograms of drinks to 8 students on average. Each student drinks 1, that is, 5 kilograms of 5 kilograms, and each student drinks 5 kilograms of 1 kg.

4. Fill in the appropriate score in the box.

10 hectare = 10 part 1 square kilometer 250 ml = 1 liter.

90 seconds = 3/2 400 m2 = 1 ha 25.

A 4-meter-long iron bar weighs 3 kilograms, with an average weight of 3 kilograms per meter.

6. The store bought 8 kg of chestnuts and sold them on the opening day, leaving 2 kg.

7. A rice mill grinds 50 kilograms of rice in 30 minutes, with an average of 5 kilograms of rice per minute. According to this calculation, it takes 3 minutes and 5 minutes to grind 1 kg.

8. Draw the largest square in a circle. The diagonal of this square is 12cm, so the area of this circle is 72cm.

9. A person's ID number is 41122419760917481. This person's date of birth is1September, 97617th, and his sex is 33 years old.

10, emergency telephone 120, alarm telephone 1 10, and fire telephone 1 19.

1 1. When setting the alarm clock, the pointer is 5cm long. After a day and a night, the needle tip passed 62.8 cm.

12, Xiao Qiang, Xiaojun and Xiaoming ran from place A to place B. It took Xiao Qiang hours, Xiaojun-0/0 minutes and Xiaoming 0. 15 hours. Among them, Xiao Qiang arrived at B first, and Xiaojun arrived last.

13. Cut out the largest circle in a rectangle 6 cm long and 4 cm wide. The circumference of this circle is 12.56 cm, and the remaining area is11.44 cm 2.

There are 24 girls and 30 boys in 14 and 5 1 class. The number of girls is 4/5 of that of boys, and the number of boys is 0.25 times that of 65438+ girls, accounting for 5/9 of the class.

15. The first person in the world to make the value of pi accurate to six decimal places is Chinese mathematician Zu Chongzhi.

Second, judge right or wrong:

1, the least common multiple of two numbers is the multiple of the greatest common factor of these two numbers. √

2. The circumference of circle A is longer than that of circle B, and the area of circle A must be larger than that of circle B.

3. The greatest common factor of two numbers is less than two numbers. ╳

4. A semicircle is also an axisymmetric figure with only one axis of symmetry. √

5, the circle has numerous symmetry axes, which can be closely arranged. ╳

Third, carefully selected:

The numerator of 1 plus 10, the denominator should be C.

A, plus 10 B, multiply 10 C, plus 18 D, uncertain.

2, a rope, a few meters left after use, compare the used and the rest.

A, more B is used, and the remaining C and D are the same, so they can't be compared.

3. Put 5g of salt into100g of water, and salt accounts for C of brine.

A.b, c, d, not sure

4. When the diameter of a circle is expanded by four times, how many times does its circumference and area expand respectively?

A. 4th and16th b,16th and 4th c, 4th and 4th d,16th and16th.

5. Four playing cards are arranged in a row. Switch the position of the 1 card and the second card first, and then move the last card to the front. After it is opened, it is 4, 7, 8, 2. It turns out that the four cards are C in order.

A 2、4、7、8、B 4、2、7、8、C 8、7、2、4 D、7、2、8、4

6. Party A and Party B each have two baskets of apples, one weighing 32 kg and the other weighing x kg. Take 4 Jin from the first basket and put it in the second basket. The two baskets of apples weigh the same. The following equation is correct d.

a、32-x=4 B、x+4=32 C、x-8=32 D、x+4=32-4

7. Xu Rongji's living room is 4.8 meters long and 4.2 meters wide. Square bricks with a side length of c decimeter are used to lay the floor without cutting.

a、4 B、5 C、6 D、8

8. There is a semicircle with a radius of r cm and a circumference of 1 cm.

a、л+2r B、л+ 1r C、лr

9 and 2 are 8 and c of 12.

A, common multiple b, minimum common multiple c, common factor d and maximum common factor

Fourth, be careful:

1, solve the equation, I have no problem!

2.5x= 1 +X=2 0.36+X= - X =

x = 0.4 x = 10 x = 0.24 x = 14 x 1。

2. How to calculate it.

There are four questions in the first line.

= 5/9-2/9- 1.

= 0 in 65438+6.

= 2/3+65438/3+0-3/8+5/8

=0

= 3/4+65438/4+0-2/5

= 3/5

= 7 choose 2+7 choose 5+4 choose 3.

= 1 3/4 again

There are four questions in the first line.

= 65438 of 6+0+5 of 6+7 of 8+65438 of 8+0

=2

= 7 of 65438+05+8 of 65438+05+7+00 of 65438-3+00 of 65438.

= 1 and 2/5

= 5 choose 4+7 choose 3

=4