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40All About Slide RulesThe slide rule does not tell us the location of the decimal point, but byestimate we know it must be 42, not 4.2, or 420, etc. We recommend this typeof rough estimate procedure for determining the location of the decimal point.See Tricks and Time Savers chapter for other methods of locating the decimalpoint.Answer: 10.44 on D atcursorNext try: 3.6 X 2.9Left index of C to 36 on DNow we try to set the cursor to 29 on C, but it is about a centimeter off thescale.So, switch indexes.Right index of C to 36 on DCursor to 29 on CHow can we be confident about the last digit ... 4? Look at where the cursorpoints on D. It is somewhere between 104 and 105. In the original problem, thelast digits of the numbers we are multiplying are 6 and 9.6 times 9 = 54 ... and the last digit of 54 is 4.So, 3.6 times 2.9 must end with a 4.Therefore, the cursor is at 10.44 on DEstimate for decimal point: 4 times 3 = 12. So the answer is 10.44We cannot always use this technique for finding the last digit in our answer.For instance, if we multiply two numbers that have 3 digits each, then theanswer would have 5 or 6 significant digits, which is beyond the ability of sliderule reading.Answer: 10.44 on D at atleft index of CAnswer: 10.44. on DF atcursorAnswer: 10.44. on DF atcursorAnswer: 10.44 on A atcursorTry: 3.6 X 2.9 using the CI scaleCursor to 3.6 on DSlide to 2.9 at cursor on CITry: 3.6 X 2.9 using the C and CF and DF scalesRight index of C to 3.6 on D Cursor to 2.9on CFTry: 3.6 X 2.9 using only CF and DFSlide CF index under 3.6 on DFCursor to 2.9 on CFTry: 3.6 X 2.9 using only the A and B scalesLeft index of B to 3.6 on A Cursor to2.9 on B