The recurring decimal decimal can appear calculation result. That the result was clear and it could be used in further calculations, such fraction needs to be rounded. It must be done so that to minimize inaccuracy in the answer or further calculations.
It is required to you
- - knowledge of categories of decimal fractions;
- - skills of actions with decimal fractions.
Instruction
1. Be defined to what category it is necessary to round decimal fraction. Write down it to the following number after this category. For example, if it is necessary to round number with decimal fraction 3.6789468 … to thousand, then it can be written down in the form of 3.6789.
2. Look at figure which follows that category to which rounding is made. If this figure is equal 0, 1, 2, 3, 4, rewrite this number to the rounded category without changes, and all figures which go further, just reject.
3. For example, if it is necessary to round number 2.1643678 … to the 100-th, make the following sequence of actions: - find figure to which the number is rounded (in this example it is figure 6); - the following figure going after the 100-th is equal to 4. - as it enters range less than 5 (0, 1, 2, 3, 4), just reject this figure and all figures which follow it. Number 2.16 will be result of rounding to the 100-th.
4. If after the category to which rounding is made there is a figure which more than 4 (5, 6, 7, 8, 9), make other actions. Add to figure which stands still the category to which rounding is made, number 1, and reject all figures going after it.
5. For example, if it is necessary to round number 4.3458935 to thousand, make such actions: - find figure which stands still the category of thousand. In this case it is 5; - find the figure following it which is equal to 8; - it more than 4 therefore to number 5 add 1; - write down result which in this case will be equal to 4.346.
6. If the category to which rounding is made is submitted by number 9, then after addition 1 on the place of this category put 0 and add 1 to the previous category and so on. At record of the rounded fraction zero are rejected. For example, if it is necessary to round number 7.899712 to the 100-th, add to the 9th 1, write down on its place 0, and 1 add to 8. Number 7.90=7.9 will turn out.