Table 4.

Calculators make decimal points inconspicuous and ignore over-long number entry. The table shows the results of calculating the 2009 US population as a proportion of world population on a typical handheld calculator, here a Canon LS-270H, compared with values correctly rounded for an eight-digit display. In all cases, the calculator displays an incorrect result, only in one case reporting an error, and then with a relatively inconspicuous marker. (Many calculators display a small ‘E’ instead of the full word.) Compare the standard inconspicuous seven-segment decimal point in the calculator results column against its clear presentation in the column of correct values.

calculationkeystrokesresult drawn to scalecorrect value
percentageEmbedded Image 100 Embedded Image 306900000 Embedded Image 6707000000 Embedded ImageEmbedded Image4 • 575 816 3
percentageEmbedded Image 306900000 Embedded Image 6707000000 Embedded Image 100 Embedded ImageEmbedded Image4 • 575 816 3
fractionEmbedded Image 306900000 Embedded Image 6707000000 Embedded ImageEmbedded Image0 • 045 758 2