New
New
Year 5

Explain the reasons for changing two-factor multiplication calculations to three-factor calculations

I can explain the reasons for changing two-factor multiplication calculations to three-factor calculations.

New
New
Year 5

Explain the reasons for changing two-factor multiplication calculations to three-factor calculations

I can explain the reasons for changing two-factor multiplication calculations to three-factor calculations.

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Lesson details

Key learning points

  1. Times table facts can simplify multiplication calculations using the factors of a number to make the calculation easier.

Common misconception

Pupils think that the factor that must become the product of two factors is always the largest factor.

Ensure pupils are provided with a range of opportunities to break down factors, identifying where it does make a calculation easier, and also where it doesn't make the calculation easier.

Keywords

  • Array - An array is when items are arranged in rows and/or columns.

  • Factor - Factors are whole numbers which exactly divide another whole number.

  • Associative - The associative law states that it doesn't matter how you group or pair values (i.e. which we calculate first), the result is still the same. It applies for addition and multiplication.

  • Efficient - Working efficiently means finding a way to solve a problem quickly whilst also maintaining accuracy.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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6 Questions

Q1.
What is the product of 6 and 25?
Correct Answer: 150
Q2.
What is the missing factor 7 × = 84
Correct Answer: 12, twelve
Q3.
Which pair of factors would you multiply together first to create the most efficient calculation? 17 × 40 × 5 =
17 and 40
17 and 5
Correct answer: 5 and 40
Q4.
Which equation is easiest to calculate?
72 × 20 × 5 =
Correct answer: 72 × (5 × 20) =
5 × (20 × 71) =
Q5.
There are two rabbits and each rabbit eats 50 g of food a day. How much will the rabbits have eaten in total after 14 days? g
Correct Answer: 1,400, 1400, 1,400g, 1400g
Q6.
There are 4 children in the family. They all drink a 250 ml carton of milk each at breakfast. How much milk is drunk in total each week? ml
Correct Answer: 7,000, 7000, 7000ml, 7,000ml

6 Questions

Q1.
Which statement is correct about this array?
An image in a quiz
There are 2 groups of 8 × 4
There are 8 groups of 4 × 2
Correct answer: There are 4 groups of 8 x 2
Q2.
Tick all the statements or expressions that are true about the representation.
An image in a quiz
There are 2 groups of 6 × 4
2 × (6 × 4)
Correct answer: 6 × (5 × 2)
Correct answer: There are 6 groups of 5 × 2
Correct answer: 10 × 6
Q3.
Tick the array that has been divided correctly into 3 factors.
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q4.
Which pair of factors would you choose for this calculation to calculate most efficiently?
An image in a quiz
1 × 48
Correct answer: 2 × 24
3 × 16
Correct answer: 4 × 12
Q5.
Tick the correct calculations.
Correct answer: 24 × 5 = 12 × (2 × 5)
Correct answer: 32 × 5 = 16 × (2 × 5)
42 × 5 = 22 × (2 × 5)
Q6.
Andeep is calculating 5 × 48 He says he has simplified his calculation to 5 × 8 × 6 to make it easier. Which statement is correct?
This is the most efficient calculation.
Correct answer: He could simplify it further by using 4 × 12
He could simplify it further by using 2 × 24