### Vn129.1 **Robby Computes a Tax** 4/5/78

Robby caught on fire again today. He approached me inquiring,

“How much is half of 423?” Miriam responded to his question from the

other room, “2 hundred and 11 and a half.” I told her to stop butting

in and asked Robby how much was half of 400, then half of 22, then half

of 1. He came to his own conclusion of 2 hundred and 11 and a half.

But why this concern with the specific question? $423. was

the price of a swing set in a catalog the children had been perusing.

They had agreed to go halves on buying this much-desired super-toy.

I opposed their doing so and raised as an objection along the way the

observation that they hadn’t included the amount of tax they would

have to pay.

“Is there a tax on toys?” was the incredulous question. “If

food is taxed,” I responded, “should you not expect toys to be taxed

also?” When he asked how much it was, I explained to Robby that he

could think of the tax as a nickel for every dollar of the purchase

price. Here we got into complicated computations.

Robby tried to figure out how much money is 4 hundred nickels.

His confusion was great, even including such faux pas as “there are 200

nickels in a dollar.” Correcting to 20 to the dollar, he went on to

observe that $100. of the purchase price converted to $5. of tax. Here

he was stymied but began to add $5. and another. I complicated his

computation by suggesting he use the multiplication results he had

learned at school. He looked blankly at me. “How much is 4 times 5?”

I asked, and received an answer: “20.” “How much is 4 times 5 dollars?”

No answer was forthcoming. He came to $20. eventually (I believe by

adding). Robby then computed the tax for 20 dollars more (of the

original $423.), and with Gretchen’s reminder, added another 15¢ for

the last 3 dollars.

This incident required a surprising amount of time, as much

as 5 minutes, to develop.

**Relevance**

This was a very exciting incident for Robby — his first

computation of a sales tax. He brought the idea of “a tax” under

control as a comprehensible percentage, thus eliminating that

mysteriousness which has troubled his world of money since

at least last summer (cf. Vignette 54).