In the decimal system of numeration the number of 6-digit numbers in which the digit in any place is greater than the digit to the left of it, is

Options

A. 210
B. 84
C. 126
D. none of these

Explanation

To solve the problem of finding the number of 6-digit numbers in which each digit is greater than the digit to its left, we can follow these steps:

### Step 1: Understand the constraints
In a 6-digit number, each digit must be greater than the digit to its left. This means that all digits must be distinct and arranged in increasing order. Therefore, we cannot use the digit '0' as it cannot be the leading digit of a 6-digit number.

### Step 2: Identify the available digits
The available digits for our 6-digit number are from 1 to 9 (since 0 cannot be used). This gives us a total of 9 possible digits.

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