Counting is the action of finding the total number of items in a set by assigning a number to each item in a sequential manner.

The number 0 represents the absence of quantity and is the starting point in the number line.

The next number after 3 is 4.

The highest single-digit number is 9.

The number 10 is represented as 'X' in Roman numerals.

One-to-one correspondence is the principle that each item in a set corresponds to exactly one number when counting.

The counting sequence from 1 to 10 is: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.