Scientific notation: write, convert and say how many times larger

Answer Key - Grade 8 Math Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   Ari reads that a heart beats about 2,800,000,000 times in a long life. What is that, rounded to one digit times a power of 10?

   3 × 10^9
2. 2.

   Bo reads that our galaxy has about 210,000,000,000 stars. What is that, rounded to one digit times a power of 10?

   2 × 10^11
3. 3.

   Esme reads that sunlight travels about 299,792 km each second. What is that, rounded to one digit times a power of 10?

   3 × 10^5
4. 4.

   In Jun's science notes, a red cell in the body is about 0.0000075 m across. What is that, rounded to one digit times a power of 10?

   8 × 10^-6
5. 5.

   In Kira's science notes, one kind of bacterium is about 0.0000021 m long. What is that, rounded to one digit times a power of 10?

   2 × 10^-6
6. 6.

   About 8 × 10^9 people live on Earth, and about 2 × 10^4 in Noah's town. How many times as many people live on Earth?

   4 × 10^5
7. 7.

   In Pia's notes, a hair is 8 × 10^-5 m wide and a bacterium is 2 × 10^-6 m long. How many times as long is the hair's width?

   4 × 10^1
8. 8.

   A fin whale weighs about 6 × 10^4 kg, and Ren's big dog about 3 × 10^1 kg. How many times as heavy is the whale?

   2 × 10^3
9. 9.

   In Tala's notes, a speck of dust is 6 × 10^-5 m across and a virus 3 × 10^-7 m. How many times as wide is the speck?

   2 × 10^2
10. 10.

    Zee reads that the tallest mountain on Earth is about 8,849 m high. What is that, rounded to one digit times a power of 10?

    9 × 10^3