R. D. Sharma Solutions for Chapter: Playing With Numbers, Exercise 2: EXERCISE

If a number is divisible by $4$, it must be divisible by $8$.

If a number is divisible by $8$, it must be divisible by $4$.

A number is divisible by $18$, if it is divisible by both $3$ and $6$.

If a number is divisible by both $9$ and $10$, it must be divisible by $90$.

If a number exactly divides the sum of two numbers, it must exactly divide the numbers separately.

If a number divides three numbers exactly, it must divide their sum exactly.

If two numbers are co-prime, at least one of them must be a prime number.

The sum of two consecutive odd numbers is always divisible by $4$.