In this lesson we will cover how to:
- Use the Roman Numeral System;
- Compare and order the natural numbers on the number line.
Roman numeral system
We have observed in the table above some Roman numerals, so how could we know that the Roman numeral VI is the number 6?
To find out, we just need to put the Roman number V which is equal to 5 and add it to the I which is equal to 1, then we realize that VI is equal to 6.
Note1: Notice that the first Roman number (the one that appears first) is V (five) and the second is I (one), with this in mind we know that if the number that appears first is greater than the second, we can add it.
And you may ask, “teacher, what if the number that appears first is less than the second?”
Very well! Great question, we also have another observation.
Note2: When the Roman numeral that appears first is greater than the second, then we do the subtraction.
Notice in this example, the Roman numeral IV, how would we know that it is the number 4?
It’s simple, just do as we put in observation2, we know that I is the number 1, and that the Roman numeral V is the number 5, now let’s subtract 5 – 1 = 4, so we know for sure that the Roman numeral IV
Natural Numbers
This number set is very simple to learn, do you know the first numbers you learned? Remember what they were? So, the natural numbers are all the numbers that start from 0 and add 1 to 1.
Natural numbers can also be placed on a line, which we will call the number line
We have to know the idea of successor and predecessor, do you know what a successor or predecessor number is?
The successor of a number is that number that is after it, for example the number 10, what is the number after it? That’s right it’s the number 11, so the number 11 is the successor of the number 10, but you can ask “teacher but the number 12 is also after 10“, I agree with you my student, but here we have to pay attention, the successor of a number is the number itself plus 1.
I’m sure you understood the idea of a successor, because you are very intelligent! Let’s move on.
The idea of predecessor is very similar to the idea of successor, but here the predecessor is the number minus 1 itself, for example, the number 9 is the predecessor of the number 10 because 10 – 1 = 9
Comparison between natural numbers
Let’s compare some numbers, do you know if the number 7 is higher or lower than the number 20? That’s right, 7 is less than 20, but in mathematics we use some comparison symbols that I’m going to show you.
= same ≠ different
> greater than < less than
Now putting the previous example, we know that 7 is less than 20, but now we will write mathematically, so it becomes that 7< 20.
Respostas