पाटीगणित (श्रीधराचार्य - प्राचीन संस्कृत टीका एवं प्रो. कृपाशंकर शुक्ल सविस्तार व्याख्या)

MIXTURES. SIMPLE INTEREST 35
Ex. 57-58. (There are 4 bonds on which) capitals
amounting to 100, 200, 300, and 400 are given (to some one
on interest) at the rates of 2, 3, 4, and 5 per cent (per month)
in the respective order ; and months amounting to 2, 3, 5, and
4 each multiplied by 2, have passed (since the execution of
the respective bonds). Say, how would a single bond
(eka-patra) be now made out of these.¹
Ex. 59. Also say, O learned (mathematician), how a
single bond be made (out of 4 bonds) with the same capitals
as previously stated and with rates per cent (per month) of
interest augmented by ½ (in each case) and months elapsed
increased by ¼ (in each case).²
Rule for finding the time in which a capital lent out on
interest at a given rate would become a (given) multiple of
itself :
52(i). The product of the time and the argument,
being divided by the fruit and (then) multiplied by the
multiple minus one, gives the (required) time.³
Ex. 60(i). A sum of money is put to interest at 5 per
cent per month. When will it become twice of itself ?⁴
Ex. 60(ii). And when will (another sum of money) put
to interest at 3½ per cent (per month) become 1¼ of itself ?⁵
In Ex. 60(i), time = 1 month, argument = 100, fruit = 5, and
multiple = 2. Therefore the required time
1 × 100
= ------------ × (2 — 1), i.e., 20 months.
5
Similarly in Ex. 60(ii), time = 1 month, argument = 100, fruit
= 3½, i.e. 7/2, and multiple = 1¼. Therefore the required time
1 × 100 50
= ------------ × (1¼ — 1), i.e. -- months
7/2 7
== 7 months, 4 days, 17 ghaṭikās, 8 4/7 caṣakas.

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¹ Cf. GSS, vi. 78½ ; GT. p. 86, lines 25-28 (contd. on p. 87 ),
² Cf. GT, p. 87, lines 22-23.
³ Cf. BrSpSi, xii. 14 (i); GT, p. 85, line 19. Both are literally the same.
⁴ A similar example occurs in Pṛthûdaka's comm. on BrSpSi, xii.
14. The same example occurs in GT, p. 85, lines 24-25.
⁵ A similar example occurs in Pṛthûdaka's comm. on BrSpSi, xii.
14. The same example occurs in GT, p. 86, lines 4-5.