Why is it important to have categories of numbers and to know which categories you are dealing with in a given expression?

The first five terms of a linear sequence are given below. 7 , 12 , 17, 22 , 27 , what is the next term of the sequence?

Is it true that product of 3 consecutive natural numbers is always divisible by 6? justifyyour answer

10 ! a train starts from grand city and travels toward belleville 388 miles away. at the same time, a train starts from belleville and runs at the rate of 47 miles per hour toward grand city. they pass each other 4 hours later. find the rate of the train from grand city.