Multiplication & Division

Objectives

To create patterns for multiplying by two digit numbers and to devise strategies for working out multiplications using larger numbers.

Resources

Abacus 4 Textbook 3 | Squared paper | Grid Method Multiplication - Recap (YouTube)

Today's Lesson

Main Activity

For the mental warm-up for this lesson give your student sets of two fractions with different denominators and ask them to find the lowest common denominator (LCD). You may need to write these down so that your student has them to look at in front of them. Remind your student that sometimes the only way to find the lowest common denominator is to multiply the two given denominators together. Choose numbers for the denominators that are less than 10.

For example, 1/4 and 1/6 (LCD is 12); 1/3 and 1/5 (LCD is 15).

Keep the numerator as ‘1’ each time.

This video will talk you through using strategies to find the LCD.

Turn to page 23 in Abacus 4 Textbook 3.

Look at the calculations on the page together for strategies to multiply by 11.

To multiply by 11, we partition 11 into 10 and 1.

We then multiply the number by 10, then by 1 and then adding the two answers together. (This is the same as using the grid method of multiplication.)

The grid method for working out the 12 times table applies for the second section of the page.

E.g. To multiply by 12, we partition 12 into 10 and 2.

We then multiply the number by 10, then by 2 and then adding the two answers together. (This is the same as using the grid method of multiplication.)

Citations

[1] www.youtube.com