Finding multiples

Finding multiples

Pencil and paper
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Marking Student Responses
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This task is about finding multiples and common multiples.

1,  2,  3,  4,  5,  6,  7,  8,  9,  10,  11,  12,  13,  14,  15,  16,  17,  18,  19,  20

 

a)

 

Using the numbers in the box above write down

 
  i)
... all the multiples of 3.
 
___________________________________________________________________
 
  ii)
... all the common multiples of 2 and 3.
 
___________________________________________________________________
 
b)
I am a number between 5 and 25, and I am a multiple of both 3 and 5.
 
What number am I?  __________
 
c)
I am a number between 20 and 40, and I am a multiple of both 2 and 7.
 
What number am I?  __________
 
d)
I am a number between 1 and 40, and I am a multiple of 3, 5, and 6.
 
What number am I?  __________
Task administration: 
This task is completed with pencil and paper only.
Level:
4
Curriculum info: 
Maths, Number and Algebra, Number Strategies
Keywords: 
multiples, factors
Description of task: 
Students identify the multiples and common multiples of numbers between 2 and 7 within given number ranges.
Answers/responses: 
 

Y9 (03/99)
a) i)
ii)		 3, 6, 9, 12, 15, 18
6, 12, 18,		 moderate
very difficult
b)   15 easy
c)   28 moderate
d)   30 moderate
Diagnostic and formative information: 
  Common error Likely calculation Likely reason
a) i) 1, 3, 6, 9, 12, 15, 18   Sees 1 as a multiple of 3. (NOTE: 3 is a multiple of 1 but not vice versa.)
a) ii) 2, 4, 6...20 and 3, 6, 9...18   Gives all the multiples of 2 or 3 (rather than both 2 and 3).
c)
d)		 9
14		 2 + 7
3 + 5 + 6		 Adds factors together.