There are three types of engineering calculators: with the return Polish, arithmetic and formular record. There are also such calculators which support switchings of methods of input of expressions. Use of each of them has the features.

## Instruction

1. Define what method of input supports your calculator. If on it there is no key with an equal-sign, but there is a key with the arrow directed up before you - the machine with the return Polish record. Existence of a key with an equal-sign says that in the device the arithmetic method of input is used. At last, if the calculator indicator, besides segment znakomest, has also matrix, then the device is calculated on formular record. In the latter case, instead of an equal-sign on the corresponding key the word ""EXE"" or ""Enter"" can be put.

2. To make calculation on the calculator with the return Polish record, it is necessary to define sequence of performance of actions in the beginning. It becomes by the standard mathematical rules. Perform operations with two operands as follows. Enter the first operand. Press the button with an arrow up to transfer it to one register of a stack up. Enter the second operand, and only after it press a key of mathematical operation. On the indicator the result of calculation will be displayed. For performance of action with one operand just enter it, and then press the button corresponding to this action.

3. On the calculator with arithmetic record perform operations with two operands the same as on the ordinary calculator. Perform operations with one operand the same as on the machine with the return Polish record. If at the keyboard there are keys with brackets, need for determination of sequence of calculations is absent. It is necessary not to allow, however, excesses of the level of enclosure of brackets specified in the instruction. In the absence of the instruction it is possible to determine this level by practical consideration, having pressed a key with the opening bracket several times and having noted after which pressing there was an error message.

4. Into the calculator with formular record the expression is entered the same as it registers on paper. If the entry field one-line, the formulas containing fractions transform to "one-storey" by means of brackets and a division sign. If necessary, the entered expression can be modified, using keys with horizontal arrows and also the Insert, Backspace and Delete buttons (on different calculators of their name can differ). Then press the EXE or Enter key and receive result. If this result is required to be placed in the following formula, use the ANS key.

5. In many calculators some of keys are capable to perform more than one function. Simple pressing of a key corresponds to performance of that operation which name is specified directly on it. Other operations are designated near the button in any given color. To force the calculator to execute such function, it is necessary to press at first the register key having the same color (it can be called ""F"", ""2ndF"", ""S""), and then - the button near which operation necessary to you is specified.