First, the smallest number.
The ancient and huge family of natural numbers consists of all natural numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. The smallest one is "1", and the largest one can't be found. If you are interested, you can find-find.
Second, there is no maximum natural number.
Maybe you think you can find a largest natural number (n), but you will immediately find another natural number (n+ 1) greater than n, which means that you will never find the largest natural number in the family of natural numbers.
Third, "1" is indeed the smallest in the family of natural numbers.
The natural number is infinite, and "1" is the smallest of the natural numbers.
Some people disagree that "1" is the smallest natural number, saying that "0" is smaller than "1" and "0" should be the smallest natural number. This is wrong, because natural numbers refer to positive integers, and "0" is the only non-positive non-negative integer, so "0" does not belong to the family of natural numbers. "1" is indeed the smallest in the family of natural numbers.
Don't underestimate this smallest "1", which is the unit of natural numbers and the first generation of natural numbers. Humans first recognized 1, and only with 1 can we get 1, 2, 3, 4. ......
I told you the special status of "1", which is the first in a thousand miles. Don't underestimate it.
Fourth, the characteristics of the circle
1. Circle is a plane figure surrounded by a closed curve in a plane. 2. Features of the circle: beautiful appearance and easy rolling.
3. center o: the point of the center is called the center. The center is generally represented by the letter o.
After the circle is folded in half for many times, the intersection of creases is at the center of the circle, that is, the center of the circle. The center of the circle determines the position of the circle.
Radius r: The line segment connecting the center of the circle and any point on the circle is called radius. In the same circle, there are countless radii, all of which are equal. The radius determines the size of the circle.
Diameter d: The line segment whose two ends pass through the center of the circle is called the diameter. The same circle has countless diameters, and all the diameters are equal. The diameter is the longest line segment in a circle.
The inner diameter of the same circle or equal circle is twice the radius: d=2r or r=d÷2.
4. Equal circles: circles with equal radii are called concentric circles, and equal circles can be completely overlapped by translation. Concentric circles: Two circles with coincident centers and unequal radii are called concentric circles.
5. The circle is an axisymmetric figure: if a figure is folded in half along a straight line, the figures on both sides can completely overlap, and this figure is an axisymmetric figure. The straight line where the crease lies is called the symmetry axis.