Maths Year 5 Autumn Multiplication and Division

Day 1 Teaching
Find common multiples. Use the ITP Number Grid to highlight multiples of 3 and 2, and then show that common multiples are all multiples of 6. Repeat for other common multiples.
Group Activities
-- Use a Venn diagram to sort multiples, placing common multiples in the intersection.
-- Find pairs of numbers which have common multiples, using a Venn diagram to help.

Day 2 Teaching
Write 24. What numbers go into 24 exactly? Take feedback. Remind children that numbers which divide into 24 exactly are factors of 24. Together make an ordered list: 1, 24; 2, 12; 3, 8; 4, 6. Point out systematic approach. Repeat for 27 and 36.
Group Activities
-- Find the number less than 50 with the greatest number of factors, find numbers which have an even number of factors and numbers which have an odd number of factors.

Day 3 Teaching
Display word problems one at a time: Agree calculation for each. Solve. Discuss if answer should be rounded up or down. Challenge children to think of a problem where they would round up, and one to round down.
Group Activities
Use the ‘Long As You Like’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Use sketches/cubes to represent division problems to help determine if answers need to be rounded up or down.

• ITP: Number Grid (see resources)
• Post-it notes
• 1-10 number cards
• 12 x 12 multiplication square (see resources)
• Division word problems (see resources)
• Cubes or counters

Day 1
Times tables (pre-requisite skills)

Suggested for Day 2
Double and halve numbers to 100 (simmering skills)

Suggested for Day 3
Bar charts (simmering skills)

Day 1
Children play common multiples game.

Day 2
Find factors of 2-digit numbers.

Day 3
Solve division word problems with rounding.

• Are there more or fewer common multiples of 2 and 3 under 30 than of 3 and 5? Explain your answer?
• Write common multiples of 2, 3 and 4 up to 40.
  Write common multiples of 3, 4 and 5 up to 40.
  Which set has more numbers?
• True or false?
  5 is a factor or 20 and a factor of 40.
  3 is a factor of 7 numbers less than 20.
  15 is a factor of 100.
• Sunil says that whenever a problem involves working out the number of cars or coaches needed we have to round up. Is he correct?
• Invent a problem where the remainder is the answer.

In-depth Investigation: Long as You Like
Children create chains of numbers by finding factors and multiples. Their aim is to create the longest chain possible.

Array or Disarray
Making different arrays using a given number as an introduction to factors

Day 1 Teaching
Write: 325, 420, 500, 360, 111, 674, 261 and 472. Discuss how we know if numbers are divisible by 2, 5 and 10. What about 3? Model how to test multiples of 3 and 9. Discuss multiples of 6 and 4.
Group Activities
-- Create a rule for divisibility by 6.
-- Use rules of divisibility for 3, 4 and 5 to write numbers which are divisible by two of the numbers, only one or neither.

Day 2 Teaching
Write the following numbers on the board: 13, 15, 18, 21, 23, 24, 30. Play a game scoring points for numbers which divide into these. Establish that 23 gets almost no points. Discuss prime and composite nos.
Group Activities
Use the ‘Prime Differences’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Work in pairs to try and find all the prime numbers to at least 50.

Day 3 Teaching
Write 68 ÷ 8. Ask children to use tables to find the answer mentally, i.e. 8 r4. Discuss how to write this as 4/8 or ½. Do divisions mentally within tables using fractions and decimal equivalences for remainders.
Group Activities
-- Choose a number on the grid to divide by the number on a dice. Score one point for each of the four different ways they can say the answer (with remainder, as mixed number, as decimal and as money).
-- Come up with divisions with given answers.

• ITP: Number grid (see resources)
• Calculators
• 1–6 dice
• 1-100 grids
• blank dice

Day 1
Times tables (pre-requisite skills)

Suggested for Day 2
Double numbers to 100 (simmering skills)

Day 3
Multiplication and division facts (pre-requisite skills)

Day 1
Write 3-digit numbers in Carroll diagrams with divisible/not divisible headings.

Day 2
Find prime numbers.

Day 3
Work out mental division writing answers with remainders, as mixed numbers, as decimals and as money.

• Prime numbers are often either side of a multiple of 6. Write the two prime numbers of which this is not true.
• Explain why 1 is not a prime number.
• Write 30 as the sum of prime numbers in two different ways.
• Complete these sentences, writing either a proper fraction or a decimal <1.
  ☐ = 0.25
  1/3 > ☐
  6/8 = ☐
  ☐ < 2/4
• Write two divisions which have an answer which ends in .75 or 3/4.

In-depth Investigation: Prime Differences
Children find out if prime numbers become less frequent as we consider sets of larger numbers.

This unit has no separate Extra Support activities.

Day 1 Teaching
Write 234 × 6. Remind children of grid method. Children use grid method to do 234 × 8. Rpt for 276 × 6 and 358 × 7. Show how to use rounding to estimate answers. Work them all out.
Group Activities
-- Whole class investigation: work in groups to use the digits 4, 5, 6 and 7 to find the 3-digit x 1-digit multiplication with smallest and biggest answers (grid method).

Day 2 Teaching
Today we learn a new method called ‘short multiplication’ – it takes up less space than grid method. Write 3 × 326 and ask children to work this out using grid. Model short multiplication. Repeat for 5 x 261.
Group Activities
-- Support children using the new method of short multiplication.
-- Identify ranges of multiple of 10 for answers to grid multiplication, and say which multiple of 100 will be nearer.

Day 3 Teaching
How many meals do you eat in a year?! Agree that in most years there are 365 days and we mostly eat 3 meals a day. Together use short multiplication to find the answer. Easy group check using grid.
Group Activities
Use the ‘Excellent Eights’ in-depth problem-solving investigation below as today’s group activity.
Or, use these activities:
-- Begin to use short x to multiply 4-digit numbers by 1-digit numbers.

Day 4 Teaching
Ask diff children to do each stage. Write 6 × £5.24. Estimate an answer. Use grid method to record steps. Stress writing £ and p by each product to be clear.
Group activities
-- Support children using the grid method or new method of short multiplication for multiplying amounts of money.

• Mini-whiteboards and pens
• 0 to 9 digit cards
• Multiplying 3-digit by single-digit numbers (see resources)
• Whole class practice (see resources)
• Find the cost (whole class practice), (see practice sheets)
• ITP: Number Dials

Day 1
6, 60, 7 and 70 times tables (pre-requisite skills)

Day 2
Times tables (pre-requisite skills)

Suggested for Day 3
Factors and multiples (simmering skills)

Suggested for Day 4
Find the time later using 24-hour clock (simmering skills)

or
Multiply by multiples of 10 (e.g. 24 x 30) (simmering skills)

Day 1
Multiply 3-digit numbers by 1-digit numbers.

Day 2
Multiply 3-digit numbers by 1-digit numbers.

Day 3
Multiply 3-digit numbers by 1-digit numbers, estimating first.

Day 4
Find the cost of numbers of items using appropriate multiplication method.

• Find the product of 274 and 6 using two different methods. Do your answers agree?
• Explain how you can work out 235 x 4 mentally. Now check your answer using short multiplication.
• Fill in the missing digits:
  8 4 ☐ x ☐ = ☐ ☐ 0 5
• Write a multiplication of one 3-digit number by 6 where the last two digits of the product are consecutive (e.g. 5, 6).

In-depth Investigation: Excellent Eights
Children explore patterns when multiplying numbers with consecutive digits by 8.
The PowerPoint can be used to guide your class through this investigation.

Grid Luck
Using the grid method to multiply 2-digit numbers by 1-digit numbers

Day 1 Teaching
Write 196 ÷ 6. Ask children to estimate an answer. Then demonstrate finding out using an empty number line and jumping 30 x 6 (180) then 2 x 6 (12). Agree a remainder of 4. Model how to lay this out vertically.
☐ × 6 = 196
30 × 6 = 180
16
2 × 6 = 12
4
196 ÷ 6 = 32 r 4
Group Activities
Use the in-depth problem-solving investigation ‘Revision Rules’ from NRICH as today’s group activity.
Or, use these activities:
-- Use the vertical layout of chunking. Make an estimate between two multiples of 10 first, and then subtract the largest multiple of 10 of the divisor first.
-- Use both empty number line and vertical layouts, then choose a preference.

Day 2 Teaching
Display a word problem. Solve by dividing using a vertical layout. Discuss whether to round up or down. Repeat for the next problem.
Group Activities
-- Make sketches to help solve word problems.
-- Solve word problems, the check answer to division with multiplication.
-- Solve a multi-step division problem.

Day 3 Teaching
Children first estimate answers to different divisions. Then write 148 ÷ 3, 148 ÷ 4, 148 ÷ 5, 246 ÷ 5, 246 ÷ 6, 246 ÷ 8. Which of these divisions would you work out mentally?
Group Activities
-- Find answers to divisions, writing the answers as mixed numbers.
-- Spot divisions with the same answer, and write others with the same answer.
Identify which divisions can be done mentally, and why.

• Mini-whiteboards and pens
• Division sheet (see resources)
• Rounding up and down sheet (see resources)

Day 1
Multiplication and division facts (pre-requisite skills)

Suggested for Day 2
Place 5-digit numbers on a human number line (simmering skills)

Suggested for Day 3
Convert between units of time (simmering skills)

Day 1
Practise division.

Day 2
Solve division word problems; round up or down.

Day 3
Practise using the vertical layout to divide numbers, spotting the occasional division that can be worked out mentally.

• Explain why each of these three divisions should be straightforward to complete mentally:
  250 ÷ 5 =
  180 ÷ 6 =
  210 ÷ 3 =
  So, now explain how you would complete these three:
  255 ÷ 5 =
  186 ÷ 6 =
  213 ÷ 3 =
• Divide 456 by 8 using just 2 hops along a number line.
  Show the same division using vertical layout.
• Use vertical layout to find the answer to 234 ÷ 6 and say why it is possibly less straightforward than 244 ÷ 6.
• Write a division of a 3-digit number by a 1-digit number where the remainder is 5.

In-depth Investigation: Revision Rules
Make and prove conjectures when dividing larger numbers by a single digit. Revision Rules from nrich.maths.org.

Chunking Challenge
Using chunking to divide, answers between 10 and 20, no remainders

Leftovers
Using chunking to divide, answers between 10 and 20, with remainders