# N9c – Adding and subtracting in standard form

This is the students’ version of the page. Log in above for the teachers’ version.

Prerequisites
• Slides in PDF (one slide per page, suitable for importing into IWB software)

# Skill isolation: Writing a number given in standard form with a different power of 10

Sometimes it is useful to take a number given in standard form and rewrite it so that it has a different power of 10, even though this will mean the number is no longer in standard form. Use this applet to practise this skill.

# Adding and subtracting in standard form

Teacher resources

Teachers: log in to access the following:

• Slides in PPTX (with click-to-reveal answers)
• Slides in PDF (one slide per page, suitable for importing into IWB software)
• Worksheet (with space for student work)
• Handout (slides with exercises only; 4 per page for reduced printing)
Links to past exam questions

Although there are no questions involving standard form in lesson N15a – Rounding numbers and measures to an appropriate degree of accuracy, once you have learned about rounding numbers to a given amount of significant figures, you should become comfortable with rounding numbers in standard form to a given number of significant figures. For example: $$7.286 \times 10^5\text{ rounds to }7.3 \times 10^5 \text{ to 2 significant figures}$$