Estimating money

Estimating money

Pencil and paperOnline interactive
Overview
Connecting to the Curriculum
Marking Student Responses
Working with Students
This task is about estimating sums of money.

Question

Do NOT use a calculator for these tasks.
Whaea Hurunui had $5,600 in her bank account. She gave $1,995 as a donation.
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Renee said that Whaea Hurunui
had exactly $3,600 left.
boy-black-fire-hair-smaller.png
Paul said that Whaea Hurunui
had less than $3,600 left.
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Hohepa said Whaea Hurunui
had more than $3,600 left.
Who was correct?

    • Renee

    • Paul

    • Hohepa

Explain, without doing the exact calculation, how you can tell who is correct:
Level:
4
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
estimation, subtraction
Description of task: 
Students explain subtraction estimation methods used to solve a word problem.
Answers/responses: 
  Y9 (04/1999)
a)
b)		 Hohepa
Indicates estimation using
5 600 – 2 000 = 3 600
which means 5 600 – 1 995 is more than 3 600
because 2 000 is more than 1 995.
or
Other similar explanations.
[Do not accept arguments based on exact calculations.]		 difficult
(for both correct)
Diagnostic and formative information: 
   Common error Likely reason
b)    Does exact calculation rather than estimation.