Page:The Rhind Mathematical Papyrus, Volume I.pdf/122

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106
CHAPTER III—MISCELLANEOUS PROBLEMS
[69

Proof.

\ 1 222317121
\ 2 451314114128142
Total 80.

3 11/2 hekat makes 1120 ro, for

\ 1 320
\ 2 640
\ 12 160
Total 1120.

Therefore multiply 80 so as to get 1120.

Do it thus:

  1 80
\ 10 800
  2 160
\ 4 320
Total 14.

That is, one of the loaves contains 14ro, or 132 hekat 4 ro, of meal.

Proof.

  132 hekat 4 ro
  2 116164 " 3 "
  4 18132164 " 1 "
  8 14116132 " 2 "
\ 16 1218116 " 4 "
  32 11418164 " 3 "
\ 64 21214132164 " 1 "

It makes 312 hekat of meal for the 80 loaves.

The author asks two questions, first, what is the amount of meal in 1 loaf of bread, and second, how many loaves of bread one hekat of meal will make. In the solution, however, he determines first the number of loaves that one hekat will make, which he finds to be 222317121. This is the pefsu. Before determining the amount of meal in one loaf he reduces 312 hekat to 1120 ro ,so that he can say, If 80 loaves take 1120ro, 1 loaf will take 14 ro, for 80 times 14, or, what is the same thing, 14 times 80 makes 1120. The 14 ro is written in standard from as 132 4 ro, and this is the answer to the first question.

In the first multiplication it would seem as if the easiest way to get 121 would be from 17 by halving and taking 23. Perhaps originally it was obtained in that way. In the second line of the first proof there are two applications of the table at the beginning of the papyrus, the double of 17 being 14128 and the double of 121114142.