Exam note: You may use this entire page during the exam session. This page does not store calculator values permanently. Scrap Paper saves only in your browser on this device until you clear it.
Supports arithmetic, parentheses, decimals, %, powers, roots, logs, abs, reciprocal, π, and e.
Input a cumulative probability / service level as a decimal, such as 0.90, 0.95, or 0.99.
Input a z-score to find the cumulative probability / service level.
Formula: z = (x − mean) / standard deviation
Enter numbers separated by commas. Example: 10, 12, 15, 20, 23
Inventory Turns = Flow Rate / Inventory
Days of Supply = Inventory / Flow Rate
Stockout Probability = Number of stockouts / Total items
In-Stock Probability = 1 − Stockout Probability
On-Order Inventory = Lead Time × Mean demand
On-Hand Inventory = √(L + 1) × Standard Deviation × z
Holding Cost per Unit = h × (On-Order Inventory + On-Hand Inventory) / Mean demand
Forecast Error (FEt) = Actual - Forecast
Squared Error = (FEt)^2
Absolute Error = ABS(FEt)
MSE = Average of squared forecast errors
MAE = Average of absolute forecast errors
Naïve Forecast = Last realized value
Moving Average Forecast = Sum of last T realized values / T
Forecast Combination = Average of individual forecasts
Formula: ŷt+1 = (α × yt) + ((1 − α) × ŷt)
Formula: SI = Target Period Total Demand / Average Demand Across Total Time Periods
Example: SI = Total demand for a month / Average demand across all months in the year
Formula: Forecast = Smoothed Base × SI
Use when demand is steady and orders can be placed repeatedly.
Q* = sqrt((2 × K × R) / h)
Use to compare feasible quantities when there are constraints or quantity choices.
C(Q) = (K × R / Q) + (h × Q / 2)
Use when there is a single order opportunity and unsold items lose value.
Cu = Price − Cost
Co = Cost − Salvage
CR = Cu / (Cu + Co)
This panel finds z from the Critical Ratio, then computes Q* = μ + zσ.
Use when inventory is reviewed periodically and you order enough to top up to a target level S.
z = NORM.S.INV(Service Level)
Pipeline = Mean × L
Safety Stock = z × σ × sqrt(L + 1)
S = Pipeline + Safety Stock
Inventory Position = On Hand + On Order − Backorders
Order Quantity = S − Inventory Position