Range.min / max / sum / count / step

# Returns the minimum or maximum value.
range.min
range.max

# Specify a comparison criterion with a block.
range.min { |a, b| a <=> b }
range.max_by { |element| key }

# Returns the sum of all elements.
range.sum
range.sum { |element| transform }

# Returns the number of elements.
range.count
range.size  # Calculates quickly for integer ranges.

# Iterates at the specified interval.
range.step(interval) { |value| process }

range = (1..10)

# min / max: Get the minimum and maximum values.
puts range.min   # 1
puts range.max   # 10

# sum: Calculate the total (sum of 1 through 10 = 55).
puts range.sum   # 55

# Transform elements with a block before summing (sum of odd numbers only).
odd_total = range.sum { |n| n.odd? ? n : 0 }
puts odd_total   # 25 (1+3+5+7+9)

# count / size: Get the number of elements.
puts range.count  # 10
puts range.size   # 10

# Pass a block to count to filter by condition.
puts range.count { |n| n.even? }  # 5 (number of even values)

# step: Iterate at a specified interval.
(1..10).step(3) { |n| print "#{n} " }
puts  # 1 4 7 10

# Floating-point step.
(0.0..1.0).step(0.25) { |f| print "#{f} " }
puts  # 0.0 0.25 0.5 0.75 1.0

# Practical example: sum of squares from 1 to 100.
puts (1..100).sum { |n| n ** 2 }  # 338350

Range objects include the Enumerable module, so many of the same methods available on arrays work on ranges as well. min, max, sum, and count all come from Enumerable.

step can be applied not only to numeric ranges but also to date ranges (e.g., (Date.today..Date.today+7).step(1)). You can call it by passing a numeric argument directly or by using the block form.

Calling max on an exclusive range (...) returns the value just before the end. Make sure this is the maximum value you intended. Also, floating-point step may not reach the end value due to accumulated rounding errors.

For basic Range operations such as array conversion and membership checks, see Range#to_a / include? / cover?.