New
New
Year 5

# Multiply a 2-digit number by a 1-digit number using expanded multiplication (regrouping 10s to 100s)

I can use expanded multiplication to record regrouping from the 10s to the 100s.

New
New
Year 5

# Multiply a 2-digit number by a 1-digit number using expanded multiplication (regrouping 10s to 100s)

I can use expanded multiplication to record regrouping from the 10s to the 100s.

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## Lesson details

### Key learning points

1. If the product of the single digit and the tens number is greater than 100 then you regroup ten tens into one hundred.
2. If the product of the single digit and the tens number is greater than 100 the partial product will be a 3-digit number.
3. There are similarities between the representations of multiplication.

### Common misconception

Pupils may not align or regroup correctly leading to an inaccurate calculation.

Model accurately what happens when we regroup from 10s to 100s. Why did this happen? How do we record this?

### Keywords

• Expanded multiplication - Expanded multiplication is a way of recording the steps focusing on partitioning one or more factors and showing partial products.

• Regroup - The process of unitising and exchanging between place values is known as regrouping.

Ensure children can generalise that if the product of the single digit and the tens number is greater than 100 the partial product will be a 3-digit number.
Teacher tip

### 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).

## Starter quiz

### 6 Questions

Q1.
210 can be partitioned into __________.
2 tens and 2 tens
2 tens and 1 ten
2 hundreds and 0 ten
Correct answer: 2 hundreds and 1 ten
2 hundreds and 2 tens
Q2.
Lucas is chanting his 3 times tables: 3, 6, 9, ___. What comes next?
11
13
14
15
Q3.
The number 256 can be partitioned into 2 hundreds, __________ and 6 ones.
5 hundred
5 ones
Q4.
Use expanded multiplication to calculate this question: 32 × 2 =
Q5.
Calculate and sort the multiplication equations into ascending order.
1 - 45 × 0
2 - 43 × 1
3 - 41 × 2
4 - 42 × 2
5 - 44 × 2
Q6.
The product is a 2-digit number. 47, 1 and 2 are its factors. It is greater than 50. What product could it be?
Correct Answer: 94, Ninety-four, ninety four

## Exit quiz

### 6 Questions

Q1.
Look at the image. The arrow is pointing to the __________.
products
factors
recombined amount
Q2.
12 tens can be regrouped as hundred and 2 tens.
Q3.
The digits '3' and '6' in the number 365 represent:
3 tens and one 6
3 ones and 6 tens
3 hundreds and 6 ones
Correct answer: 3 hundreds and 6 tens
Q4.
Match each multiplication with the correct regrouping.

0 regroup

Correct Answer:24 × 3,Regrouping in 1s to 10s

Regrouping in 1s to 10s

Correct Answer:42 × 3,Regrouping in 10s to 100s

Regrouping in 10s to 100s

Q5.
Choose the correct partial products for this expanded method.
6 + 42