Vn65.1 Arithmetic Ripples 8/13/77
1. Miriam brought me this morning a dime she had found in the laundry.
My speculation is that it had been left in some pocket, fell out in the
wash, and was pinned in and nearly cut in half by the washing machine.
How it got on the floor where she found it I don’t know. When she
showed it to me, Miriam said, “See, Dad, somebody tried to cut this dime
in half. I bet they thought they would get two things. . . two nickels.
What a silly idea.”
2. Miriam’s most common purchase is chewing gum. She knows the going
rate for Care Free and Trident packs is 15 cents. When Gretchen went
shopping recently, Miriam gave her a quarter and a dime, placing an
order for two packs of gum.
Expecting a nickel change, Miriam asked Gretchen for it on her
return. There was no change. Gretchen explained that where she had
purchased the gum the price had been 20 cents per pack, 40 cents for
both. Miriam looked worried: “Do I owe you a nickel?” Gretchen told
her not to worry about it. Miriam muttered to herself, “20 cents, that’s
5 cents tax on each pack.”
These data are further examples of Miriam’s assigning any non-
explainable variation in price to the category of tax and her puzzle-
ment over the idea of dividing coins into fractional parts. (She does
not know about the obsolete piece-of-eight, a Spanish peso or dollar
designed to be cut into eight reals or ‘bits,’ whence our expression
‘two bits’ designating a quarter.)