So, I'll start my story with even numbers.What are even numbers?Any integer number which can be divided into two without residue, is considered even.Furthermore, even numbers on one end of this series of figures: 0, 2, 4, 6 or 8.
example: -24, 0, 6, 38 - all even numbers.
m = 2k - a general formula of writing even numbers, where k - integer.This formula may be necessary to solve many problems or equations in the primary grades.
There is another kind of numbers in the vast realm of mathematics - is the odd numbers.Any number that can not be divided evenly into two, and when divided into two residue is unity, called odd.Any one of them ends up on one of these numbers: 1, 3, 5, 7 or 9.
example of odd numbers: 3, 1, 7 and 35.
n = 2k + 1 - is a formula that you can userecord any odd number, where k - integer.
Addition and subtraction of even and odd numbers
In addition (or subtraction) of even and odd numbers have a certain regularity.We presented her with the help of the table, which is below, in order to make it easier to understand and remember the material.
| Operation | result | example |
| An even + even | An even | 2 + 4 = 6 |
| An even + odd | Odd | 4 + 3 = 7 |
| odd + odd | An even | 3 + 5 = 8 |
Even andodd numbers behave as if to subtract rather than summarize them.
Multiplication of odd and even numbers
Multiplying odd and even numbers behave naturally.You will be known in advance, the result will be odd or even.The table below shows all the possible options for better absorption of information.
| Operation | result | example |
| An even * An even | An even | 2 * 4 = 8 |
| An even * odd | An even | 4 * 3 = 12 |
| Odd * Odd | Odd | 3 * 5 = 15 |
Now consider a fractional number.
decimal record number
Decimal fractions - a number with a denominator of 10, 100, 1000 and so on, which are recorded without the denominator.The whole part is separated from the decimal by a comma.
example: 3.14;5,1;6,789 - all decimals.
With decimals can produce a variety of mathematical operations such as comparison, addition, subtraction, multiplication and division.
If you want to level the two-shot, first equalize the number of decimal places, attributing them to one of the zeros, and then dropping the comma, compare them as integers.Consider this example.Compare the 5.15 and 5.1.To start equate fraction: 5.15 and 5.10.Now we write them as integers: 515 and 510, so that the first number is greater than the second, then 5.15 is greater than 5.1.
If you want to summarize the two fractions, follow this simple rule: begin with the end of the first fraction and summarize (for example) hundredths and then tenth, then the whole.With this rule, you can easily subtract and multiply decimals.
But you need to divide fractions as integers, at the end of counting, where you have to put a comma.That is, first divide the integer part, and then - the fractional.
Just decimals should be rounded.To do this, select to what rank you want to round shot, and replace the corresponding number of digits with zeros.Keep in mind, if the next discharge of this figure was in the range from 5 to 9 inclusive, the last digit, which has remained, is incremented by one.If following this discharge figure lying in the range from 1 to 4 inclusive, the last remaining unchanged.
