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Infinite Slope Stability Factor of Safety & Seepage Formula
Calculate Effective Cohesion Resistance FS_c, Pore-Pressure-Adjusted Frictional Resistance FS_phi, Total Translational Slope Factor of Safety FS, and Landslide Stability Status.
Read the guide →FinancialInformation Ratio, Tracking Error, and Treynor Ratio formulas
Evaluate active portfolio managers against a benchmark index using Active Return, Tracking Error (STDEV.S of active diffs), Information Ratio, and Beta-adjusted Treynor Ratio.
Read the guide →Behavioral Finance & Information EconomicsInformational Cascade & Bayesian Herding Formula
Calculate Bikhchandani, Hirshleifer & Welch’s (1992) Bayesian herding posterior after two sequential actions, early cascade probability 1 - 2*q*(1 - q), and false-cascade risk (1 - q)^2.
Read the guide →Plastics Manufacturing, Injection Molding Tooling & Press SizingInjection Molding Clamping Tonnage & Shot Weight Formula
Calculate Total Part+Runner Projected Area (cm²), Required Mold Clamping Force (kN), Press Clamping Rating (Metric Tons-Force at g = 9.81), and Polymer Shot Weight (g).
Read the guide →Healthcare & ClinicalInjury Severity Score (ISS) Anatomic Polytrauma Formula (LARGE & AIS)
Calculate Susan Baker’s 0–75 Injury Severity Score ISS = LARGE(AIS,1)^2 + LARGE(AIS,2)^2 + LARGE(AIS,3)^2 across the 6 Abbreviated Injury Scale (AIS 0–6) body regions—automatically assigning ISS = 75 if any region has AIS = 6.
Read the guide →Data Cleaning & TextInspect Character Code Sequences & Split a String into Characters (CODE & MID)
Audit 4-character SKU prefixes, currency codes, or short tokens by extracting each character with MID and inspecting its numeric code point with CODE.
Read the guide →FinancialInsurance Loss Ratio, Expense Ratio & Combined Ratio formulas
Calculate loss, expense and combined ratios with an explicit earned/written premium convention, then subtract investment income relative to earned premium.
Read the guide →Engineering & ScienceInteger Quantum Hall Resistance (RK / nu) & Landau Level Cyclotron Gap Formula
Calculate quantized Hall plateau resistance R_xy = R_K / nu (where von Klitzing's constant R_K = h / e^2 = 25,812.80745 Ohms) and Landau level cyclotron spacing Delta_E = hbar * e * B / m_eff (in meV).
Read the guide →StatisticalINTERCEPT function: estimate fixed overhead cost where X equals zero
Separate fixed baseline overhead from variable unit cost with INTERCEPT, and pair it with SLOPE for transparent forecasts.
Read the guide →FinancialInterest Coverage Ratio (TIE) and Net Debt / EBITDA covenant formulas
Monitor corporate credit agreements with Times Interest Earned (EBIT / Interest), Net Leverage ((TotalDebt - Cash) / EBITDA), and automated covenant flags.
Read the guide →Financial & AccountingInterest-at-Maturity Note Clean Price & Yield (PRICEMAT & YIELDMAT Formulas)
Calculate the clean secondary-market price (PRICEMAT), dirty invoice price, and annualized yield to maturity (YIELDMAT) for certificates of deposit and notes paying interest in a single lump sum at maturity.
Read the guide →Automotive & Industrial Machine Design, Internal Expanding Drum Brakes & Shoe TorqueInternal Expanding Drum Brake Leading vs Trailing Torque
Calculate Self-Energizing Leading-Shoe Braking Torque (N·m), De-Energizing Trailing-Shoe Braking Torque (N·m), Total Simplex Drum Torque (N·m), and Shoe Wear Asymmetry Ratio.
Read the guide →Statistical & AggregationInterpolated Percentile Rank: PERCENTRANK.INC vs PERCENTRANK.EXC Formulas
Compute exact inclusive [0, 1] and exclusive (0, 1) percentile ranks with linear interpolation between bracketing observations using COUNTIF, MAXIFS, and MINIFS.
Read the guide →StatisticalInterquartile Range (IQR) formula and 1.5xIQR outlier detection fences
Measure middle-50% spread with QUARTILE.INC(r, 3) - QUARTILE.INC(r, 1) and flag potential outliers outside Tukey's Q1 - 1.5*IQR and Q3 + 1.5*IQR fences.
Read the guide →Statistical AnalysisIntraclass Correlation Shrout-Fleiss ICC(2,1) Agreement vs ICC(3,1) Consistency
Calculate single-measure and k-rater Intraclass Correlation Coefficients ICC(2,1), ICC(3,1), and ICC(2,k) from two-way ANOVA Mean Squares (MS_R, MS_C, MS_E) to isolate systematic rater bias.
Read the guide →FinancialInventory EOQ and Reorder Point formulas: Economic Order Quantity
Balance fixed ordering costs against annual holding costs with SQRT(2 * D * S / H), and set lead-time Reorder Points.
Read the guide →FinancialInventory Turnover, Days Sales of Inventory (DSI), and Cash Conversion Cycle
Measure working-capital velocity with Inventory Turnover (COGS / AvgInventory), DSI (365 / Turnover), and Cash Conversion Cycle (DSI + DSO - DPO).
Read the guide →Date & TimeInvoice Age, Days Past Due & Collection Status Escalation Formula
Calculate open days past due against an as-of reporting date while short-circuiting settled invoices first, then classify each receivable into PAID, CURRENT, PAST_DUE_1_30, PAST_DUE_31_60, or ESCALATE_60_PLUS.
Read the guide →FinancialInvoice calculation formulas: line discounts, SUMIFS subtotal, and tax-exempt flag
Build two-decimal invoice templates with per-line ROUND(Qty * Price * (1 - Disc%), 2), multi-invoice SUMIFS rollups, and Tax-Exempt customer overrides.
Read the guide →Working Capital & Commercial Trade FinanceInvoice Factoring Advance, Reserve & True APR Formula
Calculate Funded Receivable Factoring Cash Advance, Net Reserve Holdback Rebate, True Effective Annualized Cost (APR on Funded Cash), and Naive Face-Value APR Understatement.
Read the guide →Water Treatment Engineering, Ion-Exchange Softening & Boiler MakeupIon-Exchange Water Softener Hardness & Brine Salt Formula
Calculate Ion-Exchange Softener Hardness in Grains per Gallon (gpg), Total Bed Kilograin Capacity (kgr), Service Gallon Run Before Regeneration (gal), and Salt Brining Efficiency (grains/lb NaCl).
Read the guide →PCB Power Layout, IPC-2221 Copper Trace Ampacity & DC Rail Voltage DropIPC-2221 PCB Copper Trace Width & Voltage Drop Formula
Calculate IPC-2221 Required Copper Cross-Section (sq mils), Minimum PCB Trace Width (mm), Trace Series DC Resistance (mOhm), and End-to-End IR Voltage Drop (mV).
Read the guide →Statistical & Clinical AnalysisIPI & R-IPI Score Formula: Diffuse Large B-Cell Lymphoma Prognostic Index (0 to 5)
Calculate Margaret Shipp’s landmark 5-factor International Prognostic Index (IPI, 0–5: Age > 60, Stage III–IV, LDH > ULN, ECOG >= 2, Extranodal sites > 1) across standard 4-tier IPI and Sehn’s 3-tier Rituximab R-IPI.
Read the guide →FinancialIPMT function: calculate the interest portion of any loan payment period
Isolate exact monthly interest charges at the beginning, middle, or end of an amortizing loan using IPMT.
Read the guide →Equity Capital Markets & IPO SyndicateIPO Underpricing, Gross Spread & Greenshoe Formula
Calculate IPO First-Day Underpricing Pop, Jay Ritter’s Money Left on the Table, Net Issuer Proceeds after Underwriter Gross Spread, and 15% Greenshoe Over-Allotment exercise vs stabilization.
Read the guide →Healthcare & ClinicalIPSS (International Prostate Symptom Score / AUA-SI) LUTS Calculator
Sum the 7-item AUA/IPSS Lower Urinary Tract Symptom questionnaire (0–35 points: voiding vs. storage subscores) to classify BPH severity into Mild (0–7), Moderate (8–19), or Severe (20–35).
Read the guide →Statistical & EngineeringIPv4 CIDR Subnet Usable Host Count & 8-Bit Binary Octet Conversion Formula
Calculate total and usable IPv4 addresses for any /8–/32 CIDR prefix (2^(32 - prefix) - 2, honoring RFC 3021 /31 and /32 rules) and convert 0–255 octets to exact 8-bit binary strings.
Read the guide →Real Estate Taxation, IRC Section 1031 Exchanges & Carryover BasisIRC Section 1031 Like-Kind Exchange Boot & Basis Formula
Calculate IRC Section 1031 Real Estate Exchange Realized Gain ($M), Cash Plus Net Mortgage-Relief Boot under Treas. Reg. §1.1031(d)-2 ($M), Taxable Gain Recognized ($M), and Substituted Replacement-Property Tax Basis ($M).
Read the guide →Venture Capital Taxation, IRC Section 1202 QSBS & Founder ExitsIRC Section 1202 QSBS Gain Exclusion Cap (10x Basis) Formula
Calculate IRC Section 1202 Qualified Small Business Stock Per-Issuer Exclusion Cap ($M), Excluded Federal Gain ($M), Residual Taxable Gain ($M), and Federal Cash Tax Saved ($M).
Read the guide →M&A Tax Structuring, Corporate Acquisitions & IRC Section 338(h)(10)IRC Section 338(h)(10) Basis Step-Up & Tax Shield PV Formula
Calculate Joint IRC Section 338(h)(10) / 336(e) Deemed-Asset-Sale 15-Year Section 197 Annual Amortization, Annual Buyer Cash Tax Shield, Present Value of the 15-Year Tax Shield Annuity, and Net Value Created After Seller Tax Gross-Up.
Read the guide →Corporate Tax Accounting, M&A Tax Structuring & US IRC Section 382IRC Section 382 NOL Annual Limitation & Built-In Gain Formula
Calculate US IRC Section 382 Post-Acquisition Base Annual NOL Limitation (Pre-Change Equity * Long-Term Tax-Exempt Rate), Recognized Built-In Gain (RBIG) Augmented Cap, TCJA 80%-Taxable-Income-Bound Deduction, and 21% Cash Tax Shield.
Read the guide →Equity Compensation, Personal Finance & IRC Section 423 ESPP PlansIRC Section 423 ESPP 15% Lookback & Minimum Return Formula
Calculate Qualified IRC Section 423 Employee Stock Purchase Plan (ESPP) Lookback Purchase Price (85% of Lower of Grant or Purchase Price), Shares Acquired, Immediate Dollar Gain ($), and 6-Month Holding Return % across Bull and Bear Markets.
Read the guide →Startup Equity Compensation, IRC Section 83(b) & Tax PlanningIRC Section 83(b) Election Restricted-Stock Tax Formula
Calculate IRC Section 83(b) Day-1 Upfront Ordinary Tax ($k), Total Lifetime Tax With 83(b) ($k), Total Lifetime Tax Without 83(b) ($k), and Net Founder Tax Savings ($k).
Read the guide →Clinical Medicine & PhysiologyIreton-Jones Energy Expenditure Calculator: Revised 1997 Ventilator & Spontaneous ICU Equations
Estimate ICU & burn daily caloric needs without a metabolic cart using Corinne S. Ireton-Jones’s revised (1997) Ventilator-Dependent EEE(v) = 1784 - 11*Age + 5*W + 244*Male + 239*Trauma + 804*Burn and Spontaneously Breathing EEE(s) equations.
Read the guide →Coastal Hydraulics, Sea-Dike Overtopping & Wave MechanicsIribarren Surf Similarity Parameter & Wave Runup Formula
Calculate Deep-Water Wavelength L_0 (m), Iribarren Surf-Similarity Number xi_0, Smooth-Dike 2% Exceedance Wave Runup Height R_u2% (m), and Wave Breaker Regime.
Read the guide →FinancialIRR function: calculate Internal Rate of Return across uneven cash flows
Find the periodic discount rate that sets project Net Present Value to zero with IRR, and understand why cash flows need at least one sign change.
Read the guide →Financial ModelingIrregular-Date Internal Rate of Return (XIRR Equation, Newton Step & XNPV = 0 Proof)
Solve and audit exact annualized IRR on irregular calendar dates using ACT/365 day-count exponents (d_i - d_0) / 365, Newton-Raphson updates, and zero-XNPV verification.
Read the guide →Mechanical & Structural EngineeringIrwin Mode I Stress Intensity Factor K_I and Critical Crack Size Formula
Compute Mode I opening stress intensity K_I = Y * sigma * SQRT(PI() * a), fracture safety factor K_IC / K_I, and critical crack length a_crit while guarding millimeter unit traps.
Read the guide →InformationISBLANK function: why formula "" cells return FALSE and how to test both
Distinguish genuinely untouched cells (ISBLANK = TRUE) from zero-length formula strings "" and spaces.
Read the guide →Engineering & ScientificIsentropic Choked Nozzle Critical Pressure Ratio & Sonic Mass Flow Rate
Determine whether gas discharge through a relief valve or converging nozzle is subsonic or choked at Mach 1 using critical ratio (2/(gamma+1))^(gamma/(gamma-1)) and unified Saint-Venant mass flow.
Read the guide →InformationISERR function: detect broken math errors (#DIV/0!, #VALUE!) while ignoring #N/A
Separate broken calculation errors from expected #N/A missing-lookup markers using ISERR vs ISERROR.
Read the guide →InformationISERROR function: flag and count any formula error without masking values
Return TRUE for #DIV/0!, #VALUE!, #N/A, #REF!, and #NUM! using ISERROR so audit columns and pre-send checks spot broken rows immediately.
Read the guide →InformationISEVEN and ISODD: test number parity for alternating-row banding and routing
Route odd/even street numbers, badge IDs, or worksheet rows with ISEVEN and ISODD—including decimal truncation rules.
Read the guide →InformationISFORMULA function: catch hardcoded manual overrides in calculated columns
Audit financial models with ISFORMULA to spot cells where someone typed a static number over a live formula.
Read the guide →InformationISLOGICAL function: verify real TRUE/FALSE values vs text "TRUE" or 1/0
Check whether imported flag columns hold genuine logical booleans (TRUE/FALSE) rather than strings or numbers using ISLOGICAL.
Read the guide →InformationISNA function: test specifically for #N/A missing-lookup results
Return TRUE only when a lookup produces #N/A—while returning FALSE on #DIV/0! or valid matches—to reconcile unmatched IDs cleanly.
Read the guide →Cleaning imported dataISNUMBER and ISTEXT: spot numbers stored as text that SUM ignores
Diagnose why SUM under-reports imported amounts by checking each cell’s stored data type with ISNUMBER and ISTEXT before converting.
Read the guide →Cleanroom Engineering, Semiconductor Fabs & ISO 14644-1 Contamination ControlISO 14644-1 Cleanroom Particle Limit & Recovery Time Formula
Calculate ISO 14644-1 Maximum Airborne Particle Concentration Cn (particles/m³) at Size D (µm), HEPA Air Changes Per Hour (ACH), Ideal Well-Mixed 100:1 Cleanliness Recovery Time (Minutes), and EU GMP / ISO 14644-3 15-Minute Recovery Gate.
Read the guide →Mechanical Machine Design, Tribology & ISO 281 Rolling BearingsISO 281 Rolling-Bearing L10 Fatigue Life & Hours Formula
Calculate ISO 281 Bearing Load Ratio (C/P), Basic 90%-Reliability Rating Life L10 (million revolutions), Operating Service Life L10h (hours), and Continuous Operating Days.
Read the guide →Equity Compensation, IRC Section 422 ISOs & Alternative Minimum TaxISO Stock Option Bargain Element & AMT Crossover Formula
Calculate Incentive Stock Option (ISO) Form 6251 Bargain Element ($k), Tentative Minimum Tax TMT ($k), Incremental Cash AMT Payable ($k), and Maximum AMT-Free Exercise Shares (k).
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