To answer this you have to divide the given numbers by two. If you get an exact result, it means that the number you divided by two is an even number. What you want is the odd numbers; in that case it should not be divisible by two.
12 / 2 = 6 even
17 / 2 = 8.5 odd
21 / 2 = 10.5 odd
16 / 2 = 8 even
33 / 2 = 16.5 odd
19 / 2 = 9.5 odd
15 / 2 = 7.5 odd
20 / 2 = 10 even
54 / 2 = 27 even
Answer. There are 5 odd numbers ( 17, 21, 33, 19 and 15)
