Use Polya's four-step problem-solving strategy and the problem-solving procedures presented in this lesson to solve the following exercise.

Find the following sums without using a calculator or a formula.Hint: Apply the procedure used by Gauss. (See theMath Matterson page 31.)

(a)

1 + 2 + 3 + 4 + . . . +392+393+394+395

(b)

1 + 2 + 3 + 4 + . . . +545+546+547+548

(c)

2 + 4 + 6 + 8 + . . . +72+74+76+78