2.6 Multiplication Written Strategies

Unit Objectives

• We are learning to use written strategies to multiply larger numbers.

Success Criteria

• I can use an area model and extended multiplication to multiply a 1-digit number by a 2-digit number.

• I can use contracted (compact) multiplication to solve multiplication problems.

• I can choose an efficient strategy — mental or written — to solve multiplication problems, including 2-digit by 2-digit.

Learning Objective

• To multiply a 2-digit number by a 1-digit number using an area model.

Success Criteria

• I can split a 2-digit number into tens and ones.

• I can model a multiplication problem using base-10 blocks or an area model.

• I can find the total by adding the parts together.

Follow along to write notes to help you remember what you've learned.

LI: To use arrays to show how multiplication and division are connected.

Worked Example with a number line.

3 x 24 =

 - Base-10 blocks -

Learning Objective

• To use strategies to work out multiplication facts we don't have memorised yet.

Success Criteria

• I can use doubling to work out ×4 facts from ×2 facts.

• I can use the near-ten strategy to work out ×9 facts (e.g. ×10, then subtract one group).

• I can build ×6 facts by doubling ×3 facts.

The 9 near 10 strategy 

Often called the use-tens strategy is a mental math shortcut for multiplication. 

Since 9 is just (10 - 1),
you multiply by 10 instead and subtract the original number.

To multiply any number by 9:

1. Multiply the number by 10 (add a zero to the end).

2. Subtract the original number from that result.