Convert 0.00000045 to scientific notation.

Convert 0.00000045 to scientific notation.

• A. 4.5 x 10^-6
• B. 4.5 x 10^-7
• C. 0.45 x 10^-7
• D. 0.45 x 10^-6

Answer: (B)

Scientific notation writes a number as a × 10^n with the mantissa a between 1 and 10. To convert 0.00000045, take the first nonzero digits to form the mantissa: 4.5. Then move the decimal point so that it sits after that 4, which means moving it seven places to the right. Moving the decimal that many places corresponds to multiplying by 10^7, but since the original number is less than 1, the exponent is negative. This gives 4.5 × 10^-7. (Equivalent forms like 45 × 10^-8 exist, but the standard form uses a mantissa between 1 and 10.)

Scientific notation writes a number as a × 10^n with the mantissa a between 1 and 10. To convert 0.00000045, take the first nonzero digits to form the mantissa: 4.5. Then move the decimal point so that it sits after that 4, which means moving it seven places to the right. Moving the decimal that many places corresponds to multiplying by 10^7, but since the original number is less than 1, the exponent is negative. This gives 4.5 × 10^-7. (Equivalent forms like 45 × 10^-8 exist, but the standard form uses a mantissa between 1 and 10.)