For 12 to 13 year-old students. One working session.
USEFUL FOR LIFE
MEASUREMENT: WORK WITH APPROXIMATIONS (I)
We work with approximations of decimal numbers with a huge number of decimal
figures or in case of handling irrational numbers whose decimal figures are not
completely determined.
Example:
Look at number� . If we have to do any operations with number
� � 3.141592654...we can´t use the number with all its figures because we didn´t know
all of them. So we work with an approximation of � .�
In the following board you can see the different approximations-by default or
by excess- of number� :
Order of approximation
By default
( truncation technique )
By excess
0 Units 3 4
1 Tenths 3.1 3.2
2 Hundredths 3.14 3.15
3 Thousandths 3.141 3.142
4 Ten thousandths 3.1415 3.1416
So we will write � � 3.14and we will say pi is approximately equal to 3.14 when we
work with an approximation by default of � to the hundredths.
Exercise: Do a similar board with different approximations of number
2 � 1.414213562...
Order of approximation
By default
(truncation technique)
By excess
0 Units
1 Tenths
2 Hundredths
3 Thousandths