Express Numbers Using Integers Power of 10

Lucy estimated that it would take 4,000 grains of sand to make a pound. That would mean that each grain of sand weighs 1/4000 of a pound. In decimal form, that weight would be 0.00025 of a pound. Express this in scientific notation?

• 2.5 × 10^–4 pounds

• 4 × 10^–3 pounds

• 2.5 × 10^–3 pounds

• 2.5 × 10^–5 pounds

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CCSS.8.EE.A.3

Robert and Dora need to write 4,300,000,000 using scientific notation. Robert claims that 4,300,000,000 = 4.3 x 10⁸ and Dora claims that 4,300,000,000 = 4.3 x 10⁹. Whose number is correct and why?

• Robert’s number is correct because when converting 4,300,000,000, the decimal would be located between the 4 and the 3, and the original decimal point in the standard form moves to the left 8 places.

• Robert’s number is correct because when converting 4,300,000,000, the decimal would be located between the 4 and the 3, and the power of 10 is determined by the number of zeros.

• Dora’s number is correct because when converting 4,300,000,000, the decimal would be located between the 4 and the 3, and the original decimal point in the standard form moves to the left 9 places.

• Dora’s number is correct because when converting 4,300,000,000, the decimal would be located between the 4 and the 3, and the power of 10 is always the number of zeros plus 1.

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CCSS.8.EE.A.3

A researcher measured approximately 0.005123 grams of bacteria in a sample. How is this number expressed in scientific notation?

• 5.123 × 10³ grams

• 5123 × 10^–6 grams

• 0.5123 × 10^–2 grams

• 5.123 × 10^–3 grams

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CCSS.8.EE.A.3

A microscopic cell measures 3.8 x 10^-3 centimeters in diameter. What is this number in standard notation?

• 0.000038

• 0.00038

• 0.0038

• 0.038

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CCSS.8.EE.A.3

One type of ant is 0.0063 meters long. What is this length in scientific notation?

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CCSS.8.EE.A.3

How many zeros are needed to write the diameter of the nucleus of an atom in standard notation?

• 14

• 15

• 16

• 13

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CCSS.8.EE.A.3

About how many times larger than the diameter of a red blood cell is the diameter of a grain of sand? Write your answer using a power of 10

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CCSS.8.EE.A.3

Write the diameter of a red blood cell in standard notation

• 0.0000084

• 0.00000084

• 8400000

• 84000000

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CCSS.8.EE.A.3