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

Answer Key - Grade 8 Math Worksheet - Challenge Me

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

1. 1.

   Tala reads that a heart beats about 3 × 10^9 times in a long life and 6 × 10^4 times in half a day. How many times as many beats is a life?

   5 × 10^4
2. 2.

   Zee reads that our galaxy has about 2 × 10^11 stars and a star cluster about 5 × 10^3. How many times as many stars does the galaxy have?

   4 × 10^7
3. 3.

   In Ari's notes, a hair is 4 × 10^-5 m wide and a virus is 8 × 10^-8 m across. How many times as wide is the hair?

   5 × 10^2
4. 4.

   Jun reads that the Pacific holds 710,000,000 km³ of water and a big lake 4,900 km³. Rounding each to one digit, about how many times as much?

   1.4 × 10^5
5. 5.

   Kira reads that a year has 31,500,000 seconds and a lesson 2,700. Rounding each to one digit, about how many times as long is a year?

   1 × 10^4
6. 6.

   Milo's calculator shows 0.38 × 10^-4. Write it in scientific notation, then round it to one digit. What do you get?

   4 × 10^-5
7. 7.

   Noah's calculator shows 260 × 10^3. Write it in scientific notation, then round it to one digit. What do you get?

   3 × 10^5
8. 8.

   In Pia's science notes, a grown-up body has about 37,000,000,000,000 cells. What is that, rounded to one digit times a power of 10?

   4 × 10^13
9. 9.

   In Ren's science notes, a giant virus is about 0.00000072 m across. What is that, rounded to one digit times a power of 10?

   7 × 10^-7
10. 10.

    In Jun's notes, a speck of dust is 2 × 10^-5 m across and a virus 8 × 10^-8 m. How many times as wide is the speck?

    2.5 × 10^2