**Rounding** is the **process and the result of rounding** (eliminate certain figures or differences to consider an entire unit). Thanks to the rounding process, the **calculations** .

Rounding consists of **don't consider decimals** , cutting the number to stay only with the **whole** . This means, if we want to round the number **2,3** , we will eliminate the **0,3** and we will stay with him **2** . Instead, if the goal is to round **4,9** , the rounding mechanism will lead to set aside the **0,9** and to add 0.1 to be able to work with the number **5** .

With these examples we can see that rounding can be done downwards, reaching a **minor number** , or up, getting a **bigger number** . While in the first case the rounding will be carried out eliminating decimals, in the second one will have to add a **quantity** to reach the next whole number.

Rounding is not only used to operate with integers: it can also be used to eliminate any decimal. The number **8,1463** can be rounded as **8,146** or, by cutting another decimal, such as **8,15** .

A concept related to rounding is the **truncation** , which belongs to the numerical analysis (a mathematical subfield) and refers to the technique used to reduce the number of decimal digits, that is, those that are to the right of the separator, which can be a comma or a period, depending on the country. As shown in the previous paragraph, through truncation a number such as **8,1463** can happen to be **8,146** if desired **truncate it to three decimal digits** .

Rounding is common in the field of commerce, either to facilitate transactions or to replace the lack of currencies that allow too exact payment. Suppose a **person** acquires different **products** in a store and the bill to pay is **48.97 pesos** . To facilitate payment, rounding can be done on **49 pesos** . This facilitates the return of the return (the rest, also known as *return* or *change*).

It should be noted that, in some **countries** , there are laws that rounding should be in favor of the buyer. Returning to the last example, if the seller wishes to round since he does not have coins to deliver the return, he will have to do so at **48,95** or **48,90** .

**Rounding method**

Although many people familiar with mathematics use their intuition when rounding a number, there are five **rules** well defined that must be respected if you want to proceed in accordance with the conventions. Let's look at an example for each of them, in which we will always have the objective of rounding a number to its hundredths, that is, leaving only two decimal digits:

*** rule 1** : If the next digit to the right after the last one you want to keep is less than 5, then the last one should not be modified. For example: **8,453** would become **8,45** ;

*** rule 2** : in the opposite case to the previous one, when the digit following the limit is greater than 5, the last one must be increased by one **unity** . For example: **8,459** would become **8,46** ;

*** rule 3** : If a 5 follows the last digit that you want to keep and after 5 there is at least a different number from 0, the last one must be increased by one unit. For example: **6,345070** would become **6,35** ;

*** rule 4** if the last desired digit is an even number and to its right there is a 5 as the final digit or followed by zeros, then no more are done **changes** than mere truncation. For example, **4,32500** and **4,325** would become **4,32** ;

*** rule 5** : opposite to the previous rule, if the last digit required is an odd number, then we must increase it by one unit. For example: **4,31500** and **4,315** they would become **4,32** .