Seek the key questions of mathematics in the second volume of the fourth grade! !

Tree planting problem:

1, circumference of circular skating rink150m. If a lamp is installed every 15 meters along this circle, how many lamps will be pressed by a * * *?

2. Some flowerpots are arranged in a square pattern, with 8 pots on each side of the outermost layer and several pots on the outermost layer. How many potted flowers did a * * * place?

3. The distance between the Elephant Pavilion and the Orangutan Pavilion is 60 meters. The greening team should plant trees on both sides of the path between the two museums, and the distance between adjacent trees is 3 meters. How many trees will be planted?

4. Insert a colored flag of 10 on one side of the 90-meter-long runway (inserted at both ends), every two adjacent colored flags.

The distance between them is () meters.

( 1)9 (2) 10

(3) 16 (4)8

In order to welcome Children's Day on June 1st, the school held a group gymnastics performance. The fourth-grade students are arranged in a phalanx, with each station on both sides of the outermost layer 15 people. How many students are there in the outermost layer? How many students are there in the whole phalanx?

There is a 75-meter long road in front of the kindergarten. Now we should plant magnolia flowers on both sides of the road, and every two magnolia flowers are separated by 3 meters. How many magnolias can a * * plant?

Simple calculation:

Third, calculate the following questions, how to calculate how simple.

340÷( 17×4) 25×(4+8) 44×55+44×44+44

48× 125×25 10 1×56-56 560÷28

1280÷ 16÷8 4.02-3.5+0.98 77+2.7+2.3-25

4. Calculate the following questions, and simplify what can be simplified. (18)

( 125+7)×8 3200÷25×4 3.27+6.4+2.73+4.6

25×44 6.45-0.58- 1.42 12×(324-285)÷26

(2) calculation. (What can be simplified should be simplified)

30 1×79 125×72×4 728×79×272×79

8.59+2.57 X 3.43 X 5.47 49.62 X 27. 17- 19.62 15×(546-239)

18 ton -9 ton -40 kg-135 ton -6 kg (calculated in decimal) 72+28× 125-25