Writing ordinary numbers II

Writing ordinary numbers II

Pencil and paper
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This task is about writing standard form number into ordinary numbers.
 
The following facts have numbers written in standard form.
Write each of these numbers as a decimal number.
 
a)
A truck driver does a return trip from Wellington to Auckland every week.
In a year he travels approximately 6.7 × 104 km
 
= ________________________________________ km.
 
 
b)
The distance from Earth to the Moon is approximately
3.84 × 105 km.
 
= ________________________________________ km.
 

c)
The number of seconds in a century is approximately 3.155 × 109 seconds.
 
= ________________________________________ seconds.
 

 
 
d)  
The world 100 metre running record was broken by 2 × 10-2 seconds.
 
= ________________________________________ seconds.
 
e)   
The thickness of a page in a mathematics textbook is roughly 7.6 × 10-5 m.
 
= ________________________________________ m.
Task administration: 
This task is completed with pencil and paper only.
Level:
5
Curriculum info: 
Maths, Number and Algebra, Number Knowledge
Keywords: 
standard form, place value
Description of task: 
Students convert numbers from standard form to ordinary form.
Answers/responses: 
   

Y10 (09/1999)
a) 67 000 NOTE: Accept 67 000.0. easy
b) 384 000 NOTE: Accept 384 000.0. easy
c) 3 155 000 000 NOTE: Accept 3 155 000 000.0. easy
d) 0.02 moderate
e) 0.000076 difficult
Diagnostic and formative information: 
  Common error Likely reason.
a)
b)
c)		 670 000
38 400 000
3 155 000 000 000		 Inserts the number of zeros in the exponent of 10 and drops the decimal point.
a)
b)
c)		 6.70000
3.8400000
3.155000000000		 Inserts the number of zeros in the exponent of 10.
d)
e)		 002 or 0.002
0000076 or 0.0000076		 Inserts the number of zeros in the exponent of 10 before the significant figure.