Numerology

Read something about ’name-to-number’.
It was:

1 2 3 4 5 6 7 8 9
A B C D E F G H I
J K L M N O P Q R
S T U V W X Y Z

Then: sum the numbers to total and add the parts of the number.
Ex: 'TRAZAN APANSSON' = 2+9+1+8+1+5 + 1+7+1+5+1+1+6+5
=> 26 + 27 = 53
5 + 3 = 7

# I group the letters [[AJS], [BKT]] .. and so on...
letters = [*'A'..'I'].zip([*'J'..'R'], [*'S'..'Z'])

# could use 'each' and 'index'
num = ->(ch) {letters.each_with_index {|l, i| return i+1 if l.include?(ch)}; 0 }

# remove 9 until < 10
zum = ->(i) { while i > 9; i -= 9; end; i}

# main proc
to_num = ->(nm) {zum[[].tap {|ar| nm.upcase.chars {|c| ar << num[c]} }.sum]}


name = 'Oliver Cromwell'
p to_num[name]
# => 2

To shorten it…

# I could use letters = [*'A'..'Z'] and divmod
l = [*'A'..'Z']
nm = ->(c) {l.index(c).divmod(9)[1] + 1}

# i could recurse zum...
zm = ->(i) { i > 9 ? zm[i-9] : i }

# I could use map
to_num = ->(n) {
  zm[n.upcase.gsub(/[^A-Z]/, '').chars.map(&nm).sum]
}

p to_num[name]

Final code:
(using gsub to avoid ’not found')

l = [*'A'..'Z']
nm = ->(c) {l.index(c).divmod(9)[1] + 1}
zm = ->(i) { i > 9 ? zm[i-9] : i }
to_num = ->(n) {
  zm[n.upcase.gsub(/[^A-Z]/, '').chars.map(&nm).sum]
}

p to_num['Oliver Cromwell']
# => 2