Starting value / replace: The entered number becomes the running result. Earlier steps remain in the tape but are not added to this value. Example: previous result 80, enter 100 → result 100. Select this key, enter the value and confirm with =.

Add: Adds the entered number to the previous result. Example: 100 + 20 → 120. Negative values are supported too. Select +, enter the value and confirm with =.

Subtract: Subtracts the entered number from the previous result. Example: 100 − 20 → 80. Subtracting a negative number increases the result: 100 − (−20) → 120. Select −, enter the value and confirm with =.

Multiply: Multiplies the previous result by the entered number. Example: 120 × 2 → 240. Each step uses the previous result, without operator precedence. Select ×, enter the factor and confirm with =.

Divide: Divides the previous result by the entered number. Example: 120 ÷ 3 → 40. Division by zero is not possible; correct or disable the invalid step. Select ÷, enter the divisor and confirm with =.

Percentage increase: Increases the previous result by the entered percentage. Example: 100 and enter 19 → 119. Formula: previous result × (1 + percentage / 100). Use for general markups; use Gross to add tax; no tax rate is selected automatically. Select + %, enter the percentage and confirm with =.

Gross / add tax: Calculates the gross amount from the previous net amount and the entered tax rate. Example: 100 net and enter 19 → 119 gross; added tax is 19. Formula: net × (1 + tax rate / 100). No tax rate is preset. Select Gross, enter the rate and confirm with =. Net removes the included tax again.

Percentage discount: Reduces the previous result by the entered percentage. Example: 200 and enter 10 → 180, a discount of 20. Formula: previous result × (1 − percentage / 100). Successive discounts each use the remaining amount. Select − %, enter the percentage and confirm with =.

Remove included tax: Calculates the net amount from a gross amount that already includes tax. Example: 119 gross and enter 19 → 100 net. Formula: gross ÷ (1 + tax rate / 100). This is not the same as a 19 % discount! Select Net, enter the included tax rate and confirm with =.

Subtotal: Records the running result as a separate named step without changing it. Example: a “Total costs” line after materials and shipping. No number is needed. This subtotal also recalculates when earlier steps change. Select Subtotal, optionally enter a name and confirm with =.

Note: Adds a descriptive line to the tape without changing the result. Enter the text in “Step name / note”, for example “Supplier quotation”. No number is needed. Notes can be edited, moved, disabled or deleted just like other steps. Confirm with =.