A number is divisible by 5 if it ends in either 0 or 5.

A number is divisible by 9 if the sum of its digits is divisible by 9.

Factors of a number are the integers that can divide that number without leaving a remainder, while multiples are the result of multiplying that number by an integer. Hence, factors are always less than or equal to multiples.

HCF and LCM can be equal when both numbers are the same.

Modular arithmetic is primarily applicable to integers, making the first statement true.

Prime numbers are defined as having exactly two distinct positive divisors: 1 and the number itself.

The base-8 number system, also known as octal, uses digits from 0 to 7. Therefore, the correct statement is that it uses digits 0-7.

The property of modular arithmetic states that (a + b) mod n = [(a mod n) + (b mod n)] mod n.

36 is indeed a perfect square as it can be expressed as 6 x 6.

The correct statement is that HCF * LCM = Product of the numbers.

Zero is neither positive nor negative in any number system.

'100' in base 3 is calculated as 1*3^2 + 0*3^1 + 0*3^0 = 9.

In hexadecimal, 'A' represents the decimal value 10.

36 is a perfect square as it can be expressed as 6 * 6.

16 is a multiple of 8, as 16 = 8 * 2.

The word 'calculation' best captures the essence of 'digital sum', as it fundamentally involves the process of adding digits.

The passage describes digital sum as innovative, reflecting its role in advancing technology.

The passage characterizes digital sum as innovative, highlighting its modern applications.