What is the number of four-digit decimal numbers (<1) in which no d...
Let the given 4 digit decimal number is
Places after decimal can be filled in the following ways:
Total number of ways = 7 x 8 x 9 x 9 = 4536
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What is the number of four-digit decimal numbers (<1) in which no d...
Counting Four-Digit Decimal Numbers with No Repeated Digits
To find the number of four-digit decimal numbers where no digit is repeated, we can follow these steps:
Step 1: Choosing the Thousands Place
- Since the number should be less than 1, the thousands place can only have digits 1, 2, or 3.
- Therefore, there are 3 choices for the thousands place.
Step 2: Choosing the Hundreds Place
- After selecting a digit for the thousands place, there are 9 digits left for the hundreds place (excluding the digit used in the thousands place).
- Hence, there are 9 choices for the hundreds place.
Step 3: Choosing the Tens Place
- After selecting digits for the thousands and hundreds places, there are 8 digits left for the tens place.
- So, there are 8 choices for the tens place.
Step 4: Choosing the Units Place
- Finally, after selecting digits for the thousands, hundreds, and tens places, there are 7 digits left for the units place.
- Thus, there are 7 choices for the units place.
Calculating the Total Number of Numbers
- To find the total number of four-digit decimal numbers meeting the given conditions, we multiply the choices for each place: 3 x 9 x 8 x 7 = 1512.
- However, since the question specifies numbers less than 1, we need to consider numbers starting from 1000 up to 9999.
- Therefore, the total number of four-digit decimal numbers less than 1 with no repeated digits is 1512 x 3 = 4536.
Therefore, the correct answer is option B) 4536.