What power of 10 is used to write the number

Seventh power of 10

Step-by-step explanation:

X > 1 so exponent will be positive and decimal point moves left. At each point divide X by 10, add 1 to exponent of 10. Exponent starts at zero.

Each time you move the decimal point one to left, you have divided the number by 10, so you have to compensate by multiplying the 10^n factor by 10, say 10 × 10^3 = 10×10×10×10 = 10^4.

12345678 = 12345678 × 10^0

= 1234567.8 × 10^1

= 123456.78 × 10^2

= 12345.678 × 10^3

= 1234.5678 × 10^4

= 123.45678 × 10^5

= 12.345678 × 10^6

= 1.2345678 × 10^7

Each time you move decimal to right, you have multiplied the number by 10, so you have to compensate by dividing the 10^n by 10, subtracting one from exponent.

0.000123 × 10^0 = 0.00123 × 10^-1

= 0.0123 × 10^-2 = 0.123 × 10^-3 = 1.23 × 10^-4

10^-2 / 10 = (1/(10×10)) / 10 = 1/(10×10×10) = 10^-3