Учебно-методическое пособие для студентов I-II курсов заочного отделения неязыковых факультетов
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- THE FACULTY OF BIOLOGY
Division of Decimal FractionsThe only difference between the division of whole numbers and that of numbers containing decimal fractions is that we must take into consideration the fact that some portion of either the dividend or the divisor or of both is fractional, as is indicated by the decimal point. Furthermore, when we perform division with whole numbers, we often cannot complete this operation as we obtain a remainder. Thus, we have before us two questions: 1. Where shall we locate the decimal point in the quotient? 2. What shall we do in the case of a remainder?
111.78 I 9 - 9 12 21 - 18 3 Note that the division of the whole part leaves a remainder 3, and that we have a fractional part 0.78. That is we are left with 3.78. From this point on we can't expect anything else but some fraction in the quotient if we continue the division. If now we bring down the next digit, that is 7, we shall have 3,7 or 370 tenths. If we divide 37 tenths by 9, we shall have a certain number of tenths in the quotient. We shall, therefore, place a decimal point after the 2 in the obtained quotient and continue the division as usual. Then we shall have: 111.78 I 9 Check: I2.42 -9 12.42 x 9 21 111.78 -18 37 -36 18 -18 Thus we observe that division of a decimal fraction by a whole number is performed in the same manner as division of a whole number by a whole number.
11 6___ -6 1.83333... 50
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2... Note that during the division above, we brought down zeroes whenever we wished to continue the process. All these zeroes assumedly come from the places to the right of the decimal point. We note that the quotient 11: 6 = 1.83333... may contain as many repeated 3's as we wish. However, if we decide to stop, less than 5, we merely drop the digits that are beyond the place where we wish to stop. THE FACULTY OF BIOLOGYThe CellAll living things are composed of cells. Very simple organisms such as yeast1 and bacteria consist of only one cell. They are one-celled or unicellular organisms. A large organism, such as a human being contains billions upon trillions of cells and is called a multicellular organism. A drop of blood, for instance, contains about forty billion cells. And there are thousands of drops of blood in the average man. Despite its small size, each cell is a tiny drop of life. Some cells can exist independently, and do, as in the case of bacteria. Human cells however, have lost that ability. They depend on one another and specialise in one function or another. Some cells specialise in photosynthesis, some in digestion, some in excretion and some in reproduction. Groups of cells of a similar shape, size and function form a tissue. When tissues of different types are grouped together for a common function they form an organ. Groups of cells, taken all together, are more advanced than single cells, even if the latter2 are more independent. The living matter inside a cell is called protoplasm. The protoplasm is divided into parts. Near the center of the cell is a part, which is denser and thicker than the rest of the cell. It is the nucleus. The rest of the cell is cytoplasm. Like any other living things, cells grow and multiply. Most cells multiply .by dividing down the middle. Then there are two cells where only one existed a moment before. The cell nucleus is in charge of seeing that cell division takes place properly. The cytoplasm takes care of the day-by-day life of the cell. Cells in different parts of the body vary in their shape according to the work they must do. Fat cells are just tiny blobs of fat surrounded by a thin layer of protoplasm. The red cells of the blood are little disks that contain a protein called haemoglobin, which carries oxygen to all other cells of the body. Red blood cells are so simple, they don't even have a nucleus and so cannot grow or divide. Nerve cells have irregular shapes with long thread-like fibers sticking out5 of them. Impulses and sensations travel along those fibers. Muscle cells are long and thin. They can contract into short, thick cells whenever necessary. Some cells are so specialised that they have abandoned almost everything but6 their main function. They have even lost the ability to multiply. A baby is born with all the brain cells, for instance, that it will ever have. Still other cells are always growing. The cells of the skin grow and divide throughout life. жүктеу/скачать 0.55 Mb. Достарыңызбен бөлісу:
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