2. There is a 20-cm-long iron wire, which is used to enclose a quadrilateral with opposite sides of 4 cm. This quadrilateral may be (parallelogram).
3. Team A and Team B complete a project in 20 days. It is known that the work efficiency ratio of Team A and Team B is 4: 5, and it takes Team A (45) days to complete the project alone.
The hour hand of a clock is 3cm long, and the distance traveled by its tip in one day and night is (12π) cm.
5. On a rectangular iron plate with a length of 10 decimeter and a width of 6 decimeters, at most (15) circular iron plates with a diameter of 2 decimeters can be intercepted.
6, 3/4 tons can be regarded as 3 tons (1/4) or 9 tons (112).
7. The side length ratio of two cubes is 1: 3, the surface area ratio of these two cubes is (1): (9), and the volume ratio is (1): (27).
8. The base angle of a triangle is 45 degrees, and its vertex angle is 90 degrees. This triangle is called isosceles right triangle.
9. A small cube with a side length of 1 cm needs at least (8) cubes to make a larger cube, and (1000) cubes to make a larger cube with a side length of 1 decimeter. If these cubes are arranged in a row, they can be arranged in (10) meters.
10, 20% of a number is 100, and 3/5 of this number is (300).
There are 48 people in class 1 1 and class 6 (1) today, and 2 people are on leave due to illness. The attendance rate on this day was (96 )%.
12, the quotient of a divided by b is 2, then A: B = (2): (1).
13, 5/8 of a is equal to 5/ 12 of b, and a: b = (12): 8.
14, the former 4∶ 15 plus 2.5, and the latter (9.375) to keep the ratio unchanged.
15,6/5 tons: 350kg, the simplified ratio is (24: 7), and the ratio is (24/7).
16. After 1/8 of the number of people in Class A is transferred to Class B, the number of people in both classes is equal. It turns out that the ratio of Class A to Class B is (4: 3).
17. The distance traveled by Party A is 4/5 of that of Party B, the time spent by Party B is 4/5 of that of Party A, and the speed ratio between Party A and Party B is (16: 25).
18, a number consists of 5 million tens, 8 thousands and 40 tens. This number is written as (5008040), rewritten as (500804) million, and the mantissa written as (500) million is omitted.
Within 19 and 50, there are only numbers with prime factor of 2 (2,8,16,32).
20. A rope is 4 meters long. It is divided into five sections on average, each section is (1/5) of this rope, and the length is (4/5) meters, which is equal to 1 meter (4/5).
The units of 2 1 and 3/8 are (1/8), and adding (4) such units is 87.5%.
22. Fill in the single-digit fraction in brackets, 3/4 < (7/9) < 4/5.
23. The least common multiple of 15+5 is (3) times the greatest common divisor, and their direct greatest common divisor is (15) times, which is the (least common multiple) of these two numbers.
24, expressed in letters:
(1) Team A completed a project in one day and Team B completed another project in two days. Cooperation between the two teams, (
1/(a+b)) days to complete?
(2) The quotient of 3 times the sum of A and 7 divided by 5 is (3/5(a+7)).
(3) The quotient of n divided by m is (n/m).
25. A wooden stick with a length of 2m and a cross-sectional diameter of 6cm has an increased surface area after being cut into four sections (
72π square centimeter), and its original volume is (1800π cubic centimeter).