Maths Revision: Multiplying Multiples of 10,100 and 1,000 12 x 50 To solve this, think of the calculation as 12 x 5 x 10 Complete your known multiplication first: 12 x 5 = 60 Then, multiply this by 10 as that’s what you divided your calculation by. So, 12 x 50 = 600 120 x 50 To solve this, think of the calculation as 12 x 5 x 100 Complete your known multiplication first: 12 x 5 = 60 Then, this time we are multiplying by 100 as there are two multiples of 10 (10 x 10 = 100) So, 120 x 50 = 6000 Maths Revision: Grid Method Multiply 2 digits by 2 43 x 29 1. Partition your 2 numbers into Tens and ones and record above your grid. 40 3 20 9 2. Multiply the values together and write the product in each box. 3. Add your products together. 40 x 20 40 x 9 3 x 20 3 x 9 800 60 360 27 800 360 60 27 + 1247
Transcript
Maths Revision: Multiplying Multiples of 10,100 and
1,000
12 x 50
To solve this, think of the calculation as 12 x 5 x 10
Complete your known multiplication first: 12 x 5 = 60
Then, multiply this by 10 as that’s what you divided your
calculation by. So, 12 x 50 = 600
120 x 50
To solve this, think of the calculation as 12 x 5 x 100
Complete your known multiplication first: 12 x 5 = 60
Then, this time we are multiplying by 100 as there are two multiples of 10 (10 x
10 = 100)
So, 120 x 50 = 6000
Maths Revision: Grid Method
Multiply 2 digits by 2
43 x 29
1. Partition your 2 numbers into Tens and
ones and record above your grid.
40 3
20
9
2. Multiply the values together and write the
product in each box.
3. Add your products together. 40 x 20
40 x 9
3 x 20
3 x 9
800 60
360 27
800
360
60
27
+
1247
TASK 1: Multiplying Multiples of 10, 100 and 1,000
Reasoning:
Zara says that she needs to use long multiplication to solve 72 x 50.
Can you suggest a different way for her to solve this calculation using number facts relating to multiples of 10, 100 and 1,000?
Problem Solving: In the calculation below, each square represents a missing digit. Find 6 possibilities to make this statement correct. You can’t use commutativity (just swapping the numbers around e.g. 40x320=320x40
Maths Revision: Multiplying using long multiplication
Option 1:
This option takes longer however some of you found
it helpful to check you had completed all of the
calculations.
This method is just like grid method—you are
partitioning each number into Hundreds, Tens and
Ones but you’re writing the answers out in a column
instead of a grid.
It is useful to write your brackets out first to check
you have included all calculations. (If you have a 4-
digit number, there will be 8 calculations to include
Th x O and Th x T)
It is also helpful to write your zeros in a different
colour (to represent multiples of 10,100 and 1000)
and cross them out when you have written them
down to ensure accuracy when multiplying by
multiples of 10, 100 and 1000.
Option 2:
This is the most efficient method of long
multiplication.
For this option, you are partitioning only your
multiplier which, in this example, is partitioning x37
into x7 and x 30.
To use this method, first write down your two
calculations in brackets.
Solve 324 x 7 using short multiplication, starting with
the ones column. Make sure to record any exchanges
and cross them out when you’ve added them.
For step 2 (324 x 30), write a 0 in the ones column to
represent it’s a multiple of 10. Once you’ve done
that, you can imagine the calculation is 324 x 3 and
solve using short multiplication again.
Add your two products together to find the answer.
As you can see, both options give you the same
answer so choose which method you prefer.
TASK 2: Multiplying 2 digits by 2 using grid method
Investigation
Use each digit card only once to write a multiplication and use grid method to solve.
A) How many different calculations are there? Try to work systematically to find all
possibilities.
B) What is the largest product you can make?
C) What is the smallest product you can make?
D) How many products are there between 1,000 and 1,500 ?
Challenge
Choose 2 calculations that you have
solved.
Write your own word problem to
represent each multiplication.
TASK 3: Multiplying using long multiplication
Use long multiplication to solve:
A) 329 x 47 B) 825 x 96
C) 958 x 28 D) 1,635 x 19
E) 3,403 F) 6,013 x 62
Use a calculator to self-mark
TASK 3: Multiplying using long multiplication
Use long multiplication to solve each multi-step word problem.
1) A machine makes 16 dice in a minute. A working day is 264 minutes.
a) How many dice are made each day? b) How many dice are made in a 5-day week?
2) A box of screws contains 513 nails. A crate contains 12 boxes
a) How many nails are there in a crate? b) A DIY store orders 24 crates. How many nails are there in total?
3) A rugby match has an average attendance of 6572 people per match. There are 32 games in a season.
a) What is the total attendance of 1 season? b) How many people attended over 2 seasons?
