Question

quantos numeros imparas ha entre 20 e 276

Answer 1

(21, 23, 25, ..., 275)
a1 + r(n-1) = an
21 + 2(n-1) = 275
2(n-1) = 275 -21
2(n-1) = 254
n-1= 254:2
n-1= 127
n = 127+1
n = 128