C # holds 2 decimal places summary of several scenarios

Scenario 1:

C # retains 2 decimal places. ToString ("F2") is OK, but if the number is three digits behind the decimal point such as 1.253, then the conversion will become 1.25. Can you just keep it to the last place, not 0?
By default, 2 bits are reserved, and if there are really 3 decimal places, 3 bits are reserved, and 4 bits are reserved for 4 bits.

Let's talk about the difference between 0 and # in ToString ("0.00##"):
0 represents the placeholder. If ToString ("0.00") preserves two decimal places, the result is two decimal places, regardless of the number of decimal places or decimals. For example 1.1234 then the result is 1.12. If it is 1.2 then the result will be 0, 1.20.
# for the back is not 0 is reserved, if it is 0 is removed. For example, ToString ("0.##") 1.20 then the result is 1.2.

For scenario 1, the default is two bits is 00, the other if the greater than two bit is not 0 is reserved, you can write the following:

Double 1.2530 ; string ret = dd. ToString ("0.00####"//  1.253

Scenario 2:

According to international practice, sometimes we need to "round" the number of digits that are exceeded. There are many ways to preserve two decimal places in C #, which are commonly summarized as follows:

1, Math.Round (0.333333,2);//According to the international standard of rounding
2, double dbdata=0.335333; String Str1=string.format ("{0:f}", dbdata);//default is two-bit reserved
3, float i=0.333333; int j= (int) (i * 100); i = j/100;
4, Decimal. Round (decimal. Parse ("0.3333333"), 2)
5, private System.Globalization.NumberFormatInfo NFI = new System.Globalization.NumberFormatInfo ();

float test=0.333333f;

Nfi. numberdecimaldigits=2;

String result=test. ToString ("N", NFI);

6, String result= String.Format ("{0:n2}", Convert.todecimal ("0.333333"). ToString ());
7, Convert.todecimal ("0.33333333"). ToString ("0.00");

C # holds 2 decimal places summary of several scenarios