Some of these we learn easily and always retain; some always seem
confusing. These can be mastered by the use of the Number Code and the
Visual picture combined. Some examples follow:
24 sheets = 1 quire, and 20 quires = one ream. The picture of Two Dozen
Squires in a Nice Room, will fix these figures and terms in mind. Two
Dozen is 24, Squires is a reminder for Quires. Nice is 20 (2 is N and 0
is C) and room a reminder for Ream.
16-1/2 Feet = 1 Rod, 320 Rods = 1 Mile. Picture a Dish and a Half
balanced on a Rod. Dish is your code word for 16 (1 is D and 6 is sh)
and the Half Dish makes 16-1/2 Feet on (in) a Rod. Next--Many's the
Rod in a Mile. Many's is 320 or the number of rods in a mile.
30-1/4 Sq. Yards = 1 Sq. Rod. Picture--MISTER takes a yard stick and
measures off a Sq. Rod. Mister is 3-0-1-4, or 30-1/4.
160 Sq. Rods = 1 Acre. Picture--See a pile of Dishes out in the Acre
being broken up by a rod. Dishes is 160 the number of Sq. Rods in an
Acre.
640 Acres in a Sq. Mile. Picture--Take the Shears and cut up the mile
into squares. Shears is 640, the number of Acres in a Sq. Mile.
792 Inches--1 Link. Picture--792 is Cabin, see the link hanging on the
side of the cabin.
4 Rods = 1 Chain. Picture--See 4 Rods wrapped around with a chain. 80
chains = 1 mile. Your Code Word for 80 is Vase; put a chain around it
and drag it a mile.
A few picture associations like these will help in fixing the difficult
points in mind. Associations which you make yourself will help you
most. Be sure to repeat them at intervals; make them permanent.