Fig. 17.—Same as Fig. 16, but for text C.
Fig. 18.—Same as Fig. 16, but for text D.
Figures 19, 20, 21, 22, and 23 all concern the first two books of the three-book text E.
Figure 19 shows the distribution of practice on 5 × 5 in the first two books of text E. The plan is the same as in Figs. 11 to 18, except that each tenth of an inch along the base line represents ten pages. Figure 20 shows the distribution of practice on 7 × 7; Fig. 21 shows it for 6 × 7 and 7 × 6 together. In Figs. 20 and 21 also, 0.1 inch along the base line equals ten pages.
Figures 22 and 23 show the distribution of practice on the divisions of 72, 73, 74, 75, 76, 77, 78, and 79 by either 8 or 9, and on the divisions of 81, 82 ... 89 by 9. Each tenth of an inch along the base line represents ten pages here also.
Fig. 19.—Distribution of practice with 5 × 5 in the first two books of the three-book text E.