Here’s why you might get unexpected results:
Operations may be calculated differently than you expect. When performing calculations, Calculator uses the fundamental “order of operations” to evaluate expressions. For example, multiplication operations are completed before addition and subtraction.
If you’re using the programmer’s calculator, it may be displaying numbers in a format you didn’t expect. Choose View > Basic or View > Scientific to use another calculator, or click the Hex, Oct, or Dec buttons to change formats.
You may be trying to perform floating-point arithmetic in the programmer’s calculator, which truncates the decimal from any floating-point result. For example, if you enter 99 / 10 =, the result is 9. Choose View > Basic or View > Scientific to use another calculator.
The precision may be set incorrectly and the calculator is rounding the result. For example, if the precision is set to zero and you enter 99 / 10 =, the result is 10. Choose View > Precision and select a different value.
You may have entered the calculation incorrectly. Choose Window > Show Paper Tape to review what you entered.