Multiplying and dividing standard form numbers

For example, what is (4 x 10 ⁷) x (5 x 10 ⁴)?

You can multiply numbers in any order, so we can multiply the two first numbers to get 20.

And we can multiply the two powers of 10 very easily - just add together the indexes, 7 and 4, to get 11.

So the answer is 20 x 10 ¹¹

However, this isn't in standard form because the first number is not between 1 and 10. However, since 20 = 2 x 10, this is the same as 2 x 10 ¹²

Exercises: [multstdformxl]

• RQuestions on standard form 3
• RQuestions on standard form 2
• RQuestions on standard form