The following is the simple solution of the three nines puzzle:—
| 9 + 9 |
|---|
| —— |
| .9 |
To divide 18 by .9 (or nine-tenths) we, of course, multiply by 10 and divide by 9. The result is 20, as required.
Table of Contents
108 .— Plato and the Nines.
288
Henry Ernest Dudeney collects a wide variety of original mathematical and mental puzzles into this volume. The book features an introductory essay on the nature of puzzles and provides solutions for all problems at the end.
The following is the simple solution of the three nines puzzle:—
| 9 + 9 |
|---|
| —— |
| .9 |
To divide 18 by .9 (or nine-tenths) we, of course, multiply by 10 and divide by 9. The result is 20, as required.