Country mile ...
1 rod (or pole or perch) = 16.5 feet or 5.5 yards (traditionally the length of pointy stick a boy needs to control a team of oxen when ploughing)
1 chain = 4 rods, or 66 feet, or 22 yards.
1 furlong = 10 chains (40 rods) = 220 yards
1 mile = 8 furlongs = 1760 yards = 5280 feet
An area of 1 furlong x 1 chain = 1 acre (traditionally an area ploughed by 1 team of oxen in one day).
Given all this and pre-decimalisation units of money (£, s, d, Guineas) and other non-metric weights & measures and a lack of calculators, it's no wonder that we were all better at mental arithmetic.
Now we only need to deal with multiples of 10s, 100s, 1000s etc. (and have calculators built into our phones).
Anyone for a long hundred of herrings?