how many 7-digit phone numbers are possible if the first digit must be non-zero? answer in scientific notation.
9*10*10*10*10*10*10
9*10^6
Write (1.8x10^-12) (2.1x10^-3)
Write (1.8x10^-12) (2.1x10^-3) in scientific notation
To determine the number of 7-digit phone numbers, we need to consider the possible values for each digit.
Since the first digit must be non-zero, there are 9 possibilities (1-9). The remaining six digits can be any number from 0-9, giving us 10 possibilities for each position.
Therefore, the total number of possible 7-digit phone numbers is calculated as:
9 × 10 × 10 × 10 × 10 × 10 × 10 = 900,000
In scientific notation, this can be written as 9 × 10^5.