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CHAPTER 4.5
In this chapter
Estimation and
Pupils should be able to:
• know when to round up
Approximation of
or down after division
when the context
requires a whole number
Decimals in Word
answer
Problems
When working with practical, real-life situations, you sometimes need to check if
the answer is reasonable and makes sense in the situation.
Think and Share
The manager of a shopping mall wants the parking bays to be 3 metres wide.
How many parking bays could be painted in a car park that is 77 metres wide?
77 -r 3 = 25.67 parking bays.
Using the rules of rounding, you would round the answer to 26 parking bays.
However, there is insufficient space for 26 parking bays. How many parking
bays should be painted?
o Spotlight 4.5.1 Estimation and approximation
in everyday lives
The «symbol is used to
show an approximation. Do you think estimation and approximation could be useful in everyday life
situations? Rounding helps you to quickly estimate a quantity. By rounding
2.99 =
3
actual values to more managable numbers, you can estimate the answers
to many problems. Estimation allows us to arrive at an answer that is "close
enough" to the actual answer. It also helps us to check if our answers are
reasonable.
Decimals
