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Mathematics oral calculation and application problems in the second volume of the fourth grade
1, and the known side lengths of rectangular boxes without covers are 4, 6 and 8㎝ respectively. What is the external area and volume of this box?

You can build a cuboid shelf by cutting it with a piece of wood 32 meters long. The length, width and height of this cuboid are all integer meters, which are all unequal. Find the volume of this cuboid.

1, surface area = 2× (4× 8+8× 6)+4× 6 = 184 (square centimeter)

Volume = 4× 6× 8 = 192 (cubic centimeter)

2. The side length of a cuboid is 12, including length, width and height;

So 32/4 = length+width+height = 8 (cm)

Because the length, width and height are different,

So the length, width and height are 1, 2,5 or 1, 3,4.

Therefore, the volume of the cuboid is:

1× 2× 5 = 10 (cubic centimeter) or 1× 3× 4 = 12 (cubic centimeter).

A rectangular playground, originally 50 meters long and 30 meters wide. After the expansion, the length and width increased by eight meters respectively. How many square meters has the playground been expanded?

(50+8)×(30+8)-50×30

=2204- 1500

=704 square meters

4. My little father was on a business trip for 56 days. It rained for two weeks on the way, and the rest was sunny. How many weeks is it sunny?

Sunny day: 56/7-2=6 (unit)