All odd numbers are prime numbers (×)
All even numbers are composite numbers (×)
Except prime numbers, all natural numbers are composite numbers (×).
If n is used to represent natural numbers, even numbers can be represented by N+2 (×).
Please classify the composite numbers of prime numbers.
The first group 4 1 50 36 42 37 29
Prime numbers: 4 1, 37, 29
Composite number: 50, 36, 42
Group II 45 53 3 1 46 42 27
Prime number: 533 1
Plural numbers: 45, 46, 42, 27
The third group 39 55 37 40 38 30
Prime number: 37
Plural numbers: 39, 55, 40, 38, 30
Multiples of classification factors 42 and 8.
6 40 7 48 32 3 2 1 24
Factor of 42: 6, 7, 3, 265, 438+0.
Multiples of 8: 40, 48, 32, 24
A tricycle carries 20 bags of cement at a time. How many times does it take to transport 100 bags of cement? What about carrying 200 bags? What about 400 or 500 packs?
The total baggage to be transported is 100 200 400 500.
Number of luggage transported each time 20 20 20 20
Shipments (5)( 10)(20)(25)
4500 ml =(4.5) l 2.56 l =(2560) ml.
3200 cubic centimeters =(3200) milliliters = (3.2) liters
Refrigerator volume (3) volume
1. greater than 2 and less than 3 is equal to
The circumference of the bottom of the cubic water tank is 20 microns. How many liters of water can this tank hold? (Ignoring glass thickness)
The side length of the cube =20÷4=5dm
So the cube volume =5×5×5= 125 cubic decimeter.
125 cubic decimeter = 125 liter
Answer: This water tank can hold 125 liters of water.
The bottom surface of the oil drum is a square with a side length of 2 cm and a height of 3 cm. Pour a barrel of this oil drum bag into a bottle with a volume of 750 ml. How many bottles can you hold?
Oil drum volume =2×2×3= 12L
12L= 12000ml
12000/750 =16 bottles
Answer: It can be packed in 16 bottles.
① There is a specialized course in the curriculum structure of primary education major in Fujian Normal University, which is divided into Chinese,