1. Guess these by writing down the numbers…
How many stars do you think are in the Milky Way?
How many kilometres away do you think our sun is from Earth?
How long do you think it would take you to fly to Mars in a rocket?
The sun is made of mainly hydrogen and helium gases. How heavy do you think a hydrogen atom is?
What do you think the diameter of a helium atom is?

2. 316,800
200 billion = 200,000,000,000
150 million = 150,000,000
About 220 days for a particular route. How many hours is This?
220 x 24 = 5280 hours = mins
grams (3.s.f)
Hydrogen is one-quarter the weight of a helium atom. m

3. Compare the power to the number of zeros.
Powers of 10
102 = 10 × 10 = 100
103 = 10 × 10 × 10 = 1,000
106 = 10 × 10 × 10 × 10 × 10 × = 1,000,000
1012 = 1,000,000,000,000
5.34 × 1,000,000
= 5.34 × 106
Powers of 10
10-2 = 𝟏 𝟏𝟎×𝟏𝟎 = 𝟏 𝟏𝟎𝟎
10-3 = 𝟏 𝟏𝟎×𝟏𝟎×𝟏𝟎 = 𝟏 𝟏𝟎𝟎𝟎
10-6 = 𝟏 𝟏𝟎×𝟏𝟎×𝟏𝟎×𝟏𝟎×𝟏𝟎×𝟏𝟎 = 𝟏 𝟏,𝟎𝟎𝟎,𝟎𝟎𝟎
5.34 × 𝟏 𝟏𝟎×𝟏𝟎×𝟏𝟎×𝟏𝟎×𝟏𝟎×𝟏𝟎
= 5.34 × 10-6

6. Write these in standard form Write these in ordinary form