It is said that mathematics is the base of all other sciences, and that arithmetic, the science of numbers, is the base of mathematics. Numbers consist of whole numbers which are formed by the digits 0,1,2,3,4,5,6,7,8 and 9, and by combinations of them. Parts of numbers smaller than 1 are sometimes expressed in terms of fractions (分数), but in scientific usage they are given as decimals (十进位). This is because it is easier to perform the various mathematical operation if decimals are used instead of fractions.
The decimal, or ten-scale, system is used for scientific purposes throughout the world. It is even accepted in countries whose national systems of weights and measurements are based upon other scales. The other scale in general use nowadays is the binary, or two-scale. In such a scale, numbers are expressed by combinations of only two digits, 0 and 1. This scale is perfectly adapted to the "off-on" pulses of electricity, and so it is widely used in computers. It is because of its simplicity that the scale is often called "the lazy schoolboy’s dream".
A knowledge of statistics is required by every type of scientists for the ysis of data. Moreover, even an elementary knowledge of this branch of mathematics is sufficient to enable the journalist to avoid misleading his readers. It is also useful in helping the ordinary citizen detect the attempts which are constantly made to deceive him.
The word "This" in the last sentence of the first paragraph refers to ______.