Addition and subtraction of natural numbers

In the previous lesson we talked about natural numbers, now let’s learn a little more about adding and subtracting them.

Addition: in this first moment, we have to know that the sum comes from an idea of joining, grouping, adding, gathering and adding the elements to the elements. For example I have 5 notebooks and I want to add 3 more notebooks, then my dear student, I ask you how many notebooks will we have in total? That’s right, we will have 8 notebooks.

Properties of addition

Neutral Element: The addition of a natural number with zero always results in the natural number. Therefore, zero does not interfere with the result, we say that it is the neutral element of addition. Example: 1 + 0 = 0 + 1 = 1

Commutative: In addition, the order of the installments does not change the result (sum). That is, if a and b are natural numbers, then: a + b = b + a.

Associative: In addition, the way of grouping the parcels does not change the sum. That is, in the addition of three numbers, associating the first two or the last two, we obtain equal results.

Let’s see: if we want to add 134, 45 and 81. Indicating in parentheses we have the following ways of representing the sum:

a) (134 + 45) + 81 b) 134 + (45 + 81) c) (134 + 81) + 45

Calculating the three expressions we will have the same result. Try it!

Subtraction: we have to have an idea similar to addition, but in subtraction we will have the idea of subtracting, reducing, withdrawing, taking away, excluding and reducing. For example, I have 10 shirts and I want to take out 7 shirts, how many shirts will I have at the end? That’s right, I’ll have 3 shirts.