Remember how decimal numbers are expressed? No? Remind the subject by reading the article Decimal numbers. Since the beginning of our lives we learn to deal with numbers, at first to show our age, and then we start comparing them, either to say who is the oldest in the room or which little friend is the tallest.
Comparing whole numbers is very easy, but what should decimal numbers be like? Don't worry, it's also very easy! Let's see how this comparison should be made.
The table below shows the number of meters each student ran in the school's marathon.
If we ask which student has covered the greatest distance, many will easily answer that it was the student Miguel, but what was the reasoning used to reach this conclusion?
Something we know how to do very well is counting numbers. In Miguel's case, we can see that none of the other students traveled a distance bigger than 34 meters. In other words, what you did was compare the integer parts of all the students' distances and notice that Miguel's integer part is bigger than everyone else's.
But how to know who ran the most, Pedro or João?
Their entire parts are equals, both traveled 33 meters, but since these are decimal numbers, we have more information to compare, so let's check the decimal places.
When need to compare the decimal part of a number, we will search for the decimal place that differentiate one number from another, so that we can know which number is higher and which is lower.
Observe the distance of these two students:
Note that the values of the two students are equal to the tenths place, being different in the hundredths. With that, we'll compare which of the two values for hundredths is larger, and then we'll find the larger value.
Hundredths:
Peter = 5 and John = 0; since 5 is greater than zero, we have that 33.15 is greater than 33.109.
Writing with the symbology of mathematics (33,15 > 33,109).
And when the hundredths are also the same? Let's compare João's and Aline's distances.
In this case we have that the whole, decimal and centesimal parts are equal. In this way, we will compare the thousandths place.
Thousandths:
Aline = 7
John = 9
So, João's part of thousandths is bigger than Aline's, that's why:
33,109 > 33,107.
Make sure you understand how to compare decimal numbers! Write the distance values in ascending order!
By Gabriel Alessandro de Oliveira
Graduated in Mathematics
