Practical arithmetic : by induction and analysis . c blocks, each 1 in. long, 1 in. wide,and 1 in. thick, are to be arranged in the form of a cube. SoLU.—First separate operation. 13824(20+4 the given number into 8000 =^4 periods, by placing dots I Root over the 4 and 3. 20X20X3 = 1200 5824 The root will consist of 20X 4X3= 240two ^gnres. 4X 4 = 16 We next find that the ~1~t^ f^ft94. largest cube contained = in 13 (thousand) is 8 (thousand), the cube root of which is 2 (tens),which place on the right, as in extracting the square root. Subtract the cube of 2 (tens), which is 8 (thousand), from
Practical arithmetic : by induction and analysis . c blocks, each 1 in. long, 1 in. wide,and 1 in. thick, are to be arranged in the form of a cube. SoLU.—First separate operation. 13824(20+4 the given number into 8000 =^4 periods, by placing dots I Root over the 4 and 3. 20X20X3 = 1200 5824 The root will consist of 20X 4X3= 240two ^gnres. 4X 4 = 16 We next find that the ~1~t^ f^ft94. largest cube contained = in 13 (thousand) is 8 (thousand), the cube root of which is 2 (tens),which place on the right, as in extracting the square root. Subtract the cube of 2 (tens), which is 8 (thousand), from thegiven number, and 5824 remain. While solving this example by figures, attend to arranging thecubic blocks. After finding that the cube root of the given number Eetiew.—292. Of what niimbens are the nine digits the cube roots ?293. What does the cube root of a number express ? 294. What the cube root of a number between 1 and 1000 ? Why ? Ofa number between 1000 and 1000000 ? Why ? What the rule for pointing ? 288 RAYS PRACTICAL will contain two places of figures, (tens and units,) and thai, thefigure in the tens place is 2, form a cube, A, 20 (2 tens) incheslong, 20 in. wide, and 20in. high; this cube will contain (Art. 92;20X20X20 = 8000 cu. in.; take this sum from the wholenumber of cubes, and 5824 cu. in. are left, which correspond tothe number 5824 in the numerical operation. It is obvious that to increase the figure Fig. 1. A, and at the same time preserve it acube, the length, breadth, and hight, musteach receive an equal addition. Then, since each side is 20 in. long,square 20, which gives 20 X 20 = 400, forthe number of sq. in. in each face of thecube; and since an addition is to be madeto three sides, multiply the 400 by 3, whichgives 1200 for the number of square inches in the 3 sides. This 1200 is called the trial divisor; because, by means of it,the thickness of the additions may be determined. By examining Fig. 2 (or the blocks, see Note 6), it
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectarithmetic, bookyear1
