12 40 41 44 54 54 55 58 59 60 61 66

their sum is 604

there are 12 numbers in total

mean(aka average) = 604/12 = 50+1/3 ≈ 50.3

mode = 54 (ie most common value, it occurs twice)

range = 66 – 12 = 54

(ie difference between highest and lowest values)

median = (54 + 55)/2 = 54.5

(ie for an odd set of numbers it is the middle one, when they are in order

for an even set of numbers it is the average of the middle two, when they are in order)

clusters there are 3 of them

40 41

54 54 55

58 59 60 61

(ie groups of numbers in a row)

gaps there are five of them

between

12 & 40

41 & 44

44 & 54

55 & 58

61 & 66

(ie gaps are gaps literally)

.