Accuracy Information

The calculator stores results internally as 13-digit numbers but displays them rounded to 10 digits or fewer, depending on the decimal format. The internal digits, or guard digits, increase the calculator’s accuracy. Additional calculations use the internal value, not the value displayed.

Rounding

If a calculation produces a result with 11-digits or more, the calculator uses the internal guard digits to determine how to display the result. If the eleventh digit of the result is 5 or greater, the calculator rounds the result to the next larger value for display.

For example, consider this problem.

1 P 3 Q 3 = ?

Internally, the calculator solves the problem in two steps, as shown below.

1.

1 P 3 = 0.3333333333333

2.

0.3333333333333 Q 3 = 0.9999999999999

The calculator rounds the result and displays it as 1. This rounding enables the calculator to display the most accurate result.

Although most calculations are accurate to within ±1 in the last displayed digit, higher-order mathematical functions use iterative calculations, in which inaccuracies can accumulate in the guard digits. In most cases, the cumulative error from these calculations is maintained beyond the 10-digit display so that no inaccuracy is shown.