# Maths KS2: Multiplying by 10, 100 and 1000

When Olivia and Hassan find themselves on the roof of an enormous skyscraper they learn how to multiply by 10, 100 and 1000 and work out the number of windows on the building.

Archimedes explains how to multiply by 10, 100 and 1000 - explaining how this method will help Olivia and Hassan work out the number of windows on the skyscraper.

Hypatia concludes the episode with a multiplication question and challenges pupils to find her mistakes in the classroom.

This short animated film is from the BBC Teach series, Hypatia's Mathematical Maze.

### Teacher Notes

Before watching the film

Prior to this lesson you may wish to introduce students to other relevant topics, for example:

• Place value appropriate to the year group
• The ten times table and its features

During watching the film

Depending on the focus of your lesson, you may wish to pause the video at certain moments to check for understanding, asking questions such as:

• How many places does the number move when multiplying by 10, 100, 1000 and 10,000?
• How many places does the number move when dividing by 10, 100, 1000 and 10,000?
• How can we tell if a number is a multiple of 10?
• Can you answer Hypatia’s final question?

Final question:

x1000x100x10Original number÷10÷100÷1000
24700024070247024724.72.740.247

x1000x100x10Original number÷10÷100÷1000
24700024070247024724.72.740.247
• x 100 - Place holders have appeared, but not in the correct places. All the digits need to move together, like the figures on a fussball table!
• ÷ 100 - The digits have been switched. Again, all the digits move in the order they were originally.

Following on from the film

• Use place value sliders to explore how the digits move when multiplying and dividing by 10, 100 and 1000.
• Use ‘backwards’ questions to explore pupils’ efficiency at manipulating the numbers, e.g. I am thinking of a number. I multiply it by 100. My answer is 3650. What was my number?
• Use digit card questions to limit possibilities, e.g. I have the digit cards 1, 2, 3, 4, 5 and 6. Use the cards to fill in the gaps. You may use each digit card once only.
• $$1 - x 100 = - ,300$$
• $$5, - 00 ÷ 100 = - 2$$
• $$- .4 ÷ 10 = 0.6 -$$

### Curriculum Notes

This short film is suitable for teaching maths at KS2 in England, Wales and Northern Ireland and 2nd Level in Scotland.