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

A way of recording the steps of a calculation focusing on partitioning one or more factors and showing partial products.

A way of recording using columns to set out and calculate a multiplication.

Multiply a 3-digit by a 1-digit number with one or two regroups

Maths

In this unit pupils will learn to multiply a 3-digit number by a single-digit number using expanded and short multiplication.  In the future unit pupils will learn why the product stays the same when one factor is doubled and the other is halved and explain the effect on the product when scaling the factors by the same amount.

In the prior unit pupils multiplied a 2-digit number by a single-digit number using partitioning and representations and used expanded multiplication and short multiplication. In this unit pupils will multiply a 3-digit number by a single-digit number using expanded and short multiplication.

Multiplication by partitioning leading to short multiplication (3 by 1-digit)

Select the correct expanded arrangement for:

Which multiplication will need regrouping in the ones column only?

Use expanded multiplication to solve: 422 × 4. Write the product in numeral form.

Use short multiplication to solve: 406 × 6. Write the product in numeral form.

What’s the next number in the sequence: 11, 22, 33, ___

Look at the short multiplication. ___ tens have been regrouped.

Look at the expanded multiplication. {{ }} tens have been regrouped.

Select the representation which shows: 42 × 3

Use a formal or informal method to solve this word problem: If all these boxes are the same height, how tall is the stack of boxes?

This lesson will soon be taken down.

Multiply a 3-digit by a 1-digit number with one or two regroups

Lesson outcome