Mathematics 5 curriculum guide 2015 I table of contents acknowledgements

Suggested Resource
• Big Ideas from Dr. Small
- 
Marian Small

---

152
MATHEMATICS 5 CURRICULUM GUIDE 2015
Specific Outcomes
MULTIPLICATION
Suggestions for Teaching and Learning
Students will be expected to:
Number
5N4.2 Apply halving and 
doubling when determining a 
given product.
5N4 Continued...
The doubling and halving strategy is a specific example of the 
multiplication principle which states: to multiply two numbers you can 
divide one factor and multiply the other by the same number without 
changing the product. 
Consider eight groups of three (8 x 3). If you combine groups of three, 
you will have six in each group, (twice as many per group), but only four 
groups (half as many groups), while the total number of circles remains 
the same. (8 x 3 = 4 x 6)
(Big Ideas from Dr. Small, 2009, p 28)
The halving and doubling strategy works best when one or more of the 
factors is even, since halving an odd number results in a fraction. This 
strategy is particularly useful for factors such as 5, 15, 25, etc. 
e.g.,
12 x 15 -> 6 x 30 -> 180
25 x 18 -> 50 x 9 -> 450
8 groups of 3 
4 groups of 6
8 x 3 = 4 x 6 (double and half)
Achievement Indicators:
5N4.1 (Continued) Determine 
the products when one factor is a 
multiple of 10, 100 or 1000 by 
annexing (adding) zeros.
When using powers of 10, students can determine the basic 
multiplication fact and then annex the correct number of zeros as 
determined by the power of ten used. For 30 x 400, for example, 
students could think “ten times one hundred is one thousand, and three 
times four is twelve, so three tens times four hundreds is twelve thousands 
or 12 000”.

---