Complete Instruction in Algebra

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Chapter 2.

Explanation of the signs + plus and - minus.

When one number is to be added to another, this is indicated by the sign +, which is placed before the number and pronounced "plus."

Thus, by 5 + 3 it is indicated that 3 is to be added to the number 5, where one then knows that 8 results: just so, for example, 12 + 7 is 19; 25 + 16 is 41, and 25 + 41 is 66, etc.

By this sign + plus, multiple numbers are also usually joined, as for example:

7 + 5 + 9, by which it is indicated that 5 is to be added to the number 7, and in addition to this 9, which amounts to 21. From this, one understands what the following formula signifies, such as:

8 + 5 + 13 + 11 + 1 + 3 + 10,

namely the sum of all these numbers, which amounts to 51.

As this is clear in itself, it is also to be noted that in a general way, numbers are indicated by letters, such as a, b, c, d, etc.; when one therefore writes a + b, this signifies the sum of both numbers which are expressed by a and b, no matter how large or small they may be. Just so, f + m + b + x signifies the sum of the numbers which are expressed by these letters.