Step by step
The question
Question: work out 4.2 × 10⁶ divided by 1.5 × 10⁻³.
4.2 × 1061.5 × 10−3
1 Group the parts
We divide the numbers, and we divide the powers of 10.
= 4.21.5 × 10610−3
2 Work out each part
4.2 divided by 1.5 is 2.8.
4.2 ÷ 1.5 = 2.8
We write 2.8 for the numbers.
= 2.8 × 10610−3
The rule: when we divide powers of the same number, here 10, we take away the powers.
6 minus −3: taking away a minus is adding.
That is 9.
10610−3 = 106 − (−3)
= 109
So the answer is 2.8 × 10⁹.
= 2.8 × 109
3 Check
Let's check the answer is in scientific notation.
2.8 is from 1 to under 10, and it is times a power of 10.
Yes!
2.8 is from 1 to under 10, times 109
Let's look back.
First: group the parts.
Then: work out each part.
Last: check.
Answer
= 2.8 × 109