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Caughey-Thomas Doping-Dependent Mobility & Wafer Resistivity (Si)
Calculate semiconductor carrier mobility μ(N) = μ_min + (μ_max - μ_min) / (1 + (N / N_ref)^α) (cm^2/(V·s)) and doped wafer resistivity ρ = 1 / (q * N * μ) across five orders of dopant concentration.
Read the guide →Healthcare & ClinicalCDAI & SDAI Rheumatoid Arthritis Disease Activity Calculator
Calculate ACR/EULAR Clinical Disease Activity Index CDAI = TJC28 + SJC28 + PtGA + PhGA (0–76) and Simplified Disease Activity Index SDAI = CDAI + CRP_mg_dL for treat-to-target RA remission.
Read the guide →FinancialCDS Credit Triangle Hazard Rate & Cumulative Default Probability formulas
Estimate a constant risk-neutral hazard rate from a spread and assumed recovery, then calculate the corresponding model survival and default probabilities.
Read the guide →Numbers and totalsCEILING.MATH, FLOOR.MATH, and ROUNDDOWN: round to multiples and full units
Round billable minutes up to 15-minute blocks with CEILING.MATH, round stock down to whole pallet multiples with FLOOR.MATH, and count complete dozens with ROUNDDOWN.
Read the guide →Conditional AggregationCell Equals, Count, or Sum One of Many Values (Allowlist COUNTIF + SUMPRODUCT)
Replace brittle 10-way OR chains with a range-driven COUNTIF allowlist flag to test, count, and sum rows matching any value in an editable lookup list.
Read the guide →EngineeringCelsius to Fahrenheit and Kelvin conversion formulas (and back)
Convert temperatures accurately between °C, °F, and Kelvin with exact 9/5 and 5/9 affine formulas.
Read the guide →High-Precision Cylindrical Finishing, Centerless Grinding Regulating Feed & Lobing GeometryCenterless Grinding Through-Feed & Workrest Angle Formula
Calculate Regulating-Wheel Surface Speed (m/min), Axial Through-Feed Rate (mm/min and m/min), and Above-Center Tangency Rounding Angle Beta (deg).
Read the guide →HVAC Energy Retrofits, Variable Frequency Drives (VFDs) & Turbomachinery Fan LawsCentrifugal Fan Affinity Laws & VFD Cubic Power Formula
Calculate VFD Turndown Airflow Q2 (m³/h), Quadratic Static Pressure Delta_P2 (Pa), Cubic Shaft Power P2 (kW), and Annual Fan Energy Savings (kWh/yr).
Read the guide →EngineeringCentrifugal Pump & Fan Affinity Laws: Flow (N), Head (N^2) & Cube Power (N^3)
Explore ideal speed scaling for flow, head and shaft power at corresponding centrifugal-pump operating points.
Read the guide →ScienceCentrifuge RCF (x g) to RPM Conversion Formula & Rotor Scaling
Convert RPM and relative centrifugal force using a specified radius in centimeters. Keep the inverse result unrounded and distinguish a numerical conversion from a permitted instrument setting.
Read the guide →Technical & Sanitaryware Ceramics, Darcy-Washburn Plaster Slip-Casting KineticsCeramic Slip Casting Parabolic Wall-Buildup Formula
Calculate Wet Cast Green Wall Thickness L = SQRT(2*K*t) (mm), Instantaneous Buildup Rate dL/dt (mm/min), Fired Ceramic Wall Thickness (mm), and Dwell Time for 8 mm Cast (min).
Read the guide →Technical Ceramics, Thermoelasticity & High-Temperature MaterialsCeramic Thermal-Shock Resistance R & R-Prime Formula
Calculate Hasselman/Kingery Severe-Quench Critical Delta-T Parameter R (K), Conduction-Weighted Parameter R-Prime (W/m), Biaxial Quench Surface Stress (MPa), and Thermal-Shock Safety Factor.
Read the guide →StatisticalCHA2DS2-VASc score arithmetic with validated flags and age bands
Practice weighted binary flags and mutually exclusive age bands using a fictional CHA2DS2-VASc example; distinguish it from the newer ESC CHA2DS2-VA approach.
Read the guide →Quantitative Finance & TradingChaikin Money Flow (CMF) Formula: Close Location Value Multiplier & Flat-Bar Guard
Calculate Marc Chaikin’s Close Location Value (Money Flow Multiplier) ((C - L) - (H - C)) / (H - L), Money Flow Volume, and 20-period CMF ratio with a halted/flat-bar zero-range guard.
Read the guide →Lookup & ReferenceChained / Nested Two-Step Lookup Across Mapping Tables (XLOOKUP)
Bridge normalized relational tables (such as Employee -> Job Band -> Bonus Target %) in a single formula by nesting one XLOOKUP or VLOOKUP as the lookup_value of a second.
Read the guide →Healthcare & ClinicalCHALICE Pediatric Head Injury CT Rule (UK NICE Age-Stratified Formula)
Evaluate Joel Dunning’s 22,772-child UK CHALICE rule—checking age-specific Infant (< 1 yr: GCS < 15 or scalp swelling > 5 cm) vs. Child (1–15 yr: GCS < 14) thresholds alongside History, Exam, and High-Energy Mechanism triggers.
Read the guide →ScienceChandrasekhar Mass Limit & White-Dwarf Radius in a Spreadsheet
Calculate a composition-dependent limiting mass and a Nauenberg-style zero-temperature radius. Keep solar and Earth units explicit, validate the model domain, and avoid treating the limit as a supernova prediction.
Read the guide →Statistical & Clinical AnalysisChao1 & Bias-Corrected Unseen Species Richness Formula: Singletons & Doubletons
Estimate true total assemblage richness (including undetected rare species, software bugs, or vocabulary words) using Anne Chao’s (1984) bias-corrected lower bound S_Chao1 = S_obs + f_1 * (f_1 - 1) / (2 * (f_2 + 1)) and Sample Inventory Completeness %.
Read the guide →Engineering & ScienceChapman-Enskog Low-Pressure Gas Viscosity Formula (Lennard-Jones)
Calculate dilute gas dynamic viscosity μ = 2.6693 * SQRT(M * T) / (σ^2 * Ω_μ) (μPa·s) from molecular weight, absolute temperature, Lennard-Jones collision diameter σ (Å), and collision integral Ω_μ.
Read the guide →TextCHAR and CODE: insert line breaks CHAR(10) and inspect hidden character codes
Generate non-keyboard characters like CHAR(10) line feeds or increment letter sequences with CHAR and CODE.
Read the guide →Statistical & Clinical AnalysisChart Error Bars Formula: Standard Error of the Mean (SEM) vs. SD & 95% CI Bounds
Avoid Excel’s default fixed-value "Standard Error" chart trap by calculating true replicate Standard Error SEM = STDEV(B2:B6) / SQRT(COUNT(B2:B6)) and custom 95% confidence bounds Mean ± 1.96 * SEM.
Read the guide →Math & StatisticalCheck & Count Exact Multiples of a Specific Pack or Lot Size (MOD = 0)
Test whether order quantities are exact multiples of case pack size N using MOD(qty, N) = 0, flag broken-case remainders, and count full-case orders across a table.
Read the guide →LogicalCheck a budget cap, allocation total, and order-pack multiples
Build TRUE/FALSE audit formulas for a budget cap, allocation weights and pack quantities. A formula result alone does not block data entry.
Read the guide →Learn with AICheck an AI forecast in a live workbook before sharing it
Turn a short sales example into a formula-based forecast, label its assumptions and test a changed month. Keep the workbook as the result, not only the chat answer.
Read the guide →EngineeringCheck Baggage Dimensions: Inches to Centimeters and Configurable Limits
Build a spreadsheet dimension check using configurable per-axis and total limits. Convert inches to centimeters and compare unrounded totals without claiming airline approval.
Read the guide →TextCheck if a cell begins or ends with specific text (prefix and suffix)
Test dynamic prefixes with LEFT(text, LEN(prefix)) and suffixes with RIGHT(text, LEN(suffix)), with optional EXACT case sensitivity.
Read the guide →Logical & ConditionalCheck If a Cell Contains a Whole Integer vs. Decimal (ISNUMBER, INT & MOD)
Validate discrete carton quantities, headcount, and serial IDs using AND(ISNUMBER(B2), B2 = INT(B2))—rejecting fractional decimals (4.25), text strings ("12"), and blank cells cleanly.
Read the guide →LogicalCheck if a cell contains all required keywords (and no excluded words)
Screen resumes, logs, or SKUs for ALL required terms, ANY optional term, and ZERO excluded terms using AND, OR, ISNUMBER, ISERROR, and SEARCH.
Read the guide →TextCheck if a cell contains any number (0–9) and count digits
Detect embedded numeric digits inside alphanumeric codes or passwords—where ISNUMBER returns FALSE—by stripping digits 0–9.
Read the guide →Date & TimeCheck If a Date Is a Workday (Exclude Weekends & Holidays)
Check a Monday–Friday work calendar against an explicit list of organization closure dates, with validation for missing dates and timestamp handling.
Read the guide →LogicalCheck if a range contains duplicates (single-cell audit gate)
Compare total non-blank entries against distinct UNIQUE values to trigger a sheet-level duplicate warning and count excess repeat rows.
Read the guide →LogicalCheck if a row is completely blank, complete, or partially filled
Classify rows as blank, Complete or Incomplete with COUNTBLANK and COLUMNS.
Read the guide →Lookup & ReferenceCheck If a Value Exists in a Range (COUNTIF & XMATCH Membership Test)
Check a nonblank ID against an approved list, distinguish literal matching from COUNTIF criteria, and test whether either of two watch-list IDs is present.
Read the guide →LogicalCheck if a value is within a percentage tolerance (±%)
Test symmetric upper and lower tolerance bands in one step with ABS(Measured - Target) / ABS(Target) <= Tolerance.
Read the guide →Date & TimeCheck if a year is a leap year (4 / 100 / 400 Gregorian rule)
Test any year or date for 366-day leap years accurately—including century exceptions like 1900 vs 2000—using MOD or DATE(yr, 2, 29).
Read the guide →Logical & Lookup FormulasCheck if All Cells in a Range Are Blank (COUNTBLANK vs COUNTA)
Test whether an entire row or multi-column block is completely blank using COUNTBLANK(B2:E2) = COLUMNS(B2:E2) (including formula empty strings "") vs strict COUNTA(B2:E2) = 0.
Read the guide →Date & TimeCheck if all dates in a column are in chronological order
Compare offset ranges A2:A4 and A3:A5 inside SUMPRODUCT to verify schedules never step backward and count out-of-order rows.
Read the guide →LogicalCheck if all values in a range are at least a minimum threshold
Verify that every cell in a batch meets a minimum score AND no cell was left blank—avoiding the MIN(range) blank-cell loophole.
Read the guide →TextCheck if cell contains specific words but NOT others (SEARCH, ISNUMBER & NOT)
Match product SKUs, support tickets, or billing descriptions that include required keywords while excluding disqualifying terms like "Trial" or "Refund".
Read the guide →LogicalCheck if multiple cells are all equal (unanimous approval check)
Verify every cell across a row holds the same non-blank value with COUNTIF and COUNTA, or enforce exact casing with EXACT.
Read the guide →LogicalCheck if multiple cells have the exact same value (Standard vs Case-Sensitive EXACT)
Compare three text codes with direct equality or case-sensitive EXACT, without treating literal wildcard characters as search patterns.
Read the guide →Logical & Lookup FormulasCheck if Multiple Columns Are Equal (Row Audit & SUMPRODUCT Count)
Verify whether three or more system export columns agree on every row using chained pairwise AND(B2=C2, B2=D2) tests and count fully synchronized rows across a table with SUMPRODUCT.
Read the guide →Date & TimeCheck if two dates are in the same month and year
Compare EOMONTH(Date1, 0) = EOMONTH(Date2, 0) so prior-year dates in the same month number never trigger false matches.
Read the guide →Lookup & ReferenceCheck submitted codes against a master list with literal comparisons
Flag missing codes and list unmatched entries without treating wildcard characters as search patterns.
Read the guide →Engineering & ScienceChen Flow-Boiling Correlation: Reynolds Factor (F) & Suppression Factor (S)
Calculate John C. Chen’s (1966) two-phase convective enhancement factor F = (1 / X_tt + 0.213)^0.736 and nucleate-boiling suppression factor S = 1 / (1 + 2.53E-6 * Re_TP^1.17) in vertical evaporators.
Read the guide →Biochemical Pharmacology & Drug DiscoveryCheng-Prusoff Competitive K_i from IC50 Formula
Convert assay-dependent half-maximal inhibitory concentration IC_50 into intrinsic competitive inhibitor affinity K_i = IC_50 / (1 + [L] / K_d) and compute uncompeted vs competed target receptor occupancy.
Read the guide →Engineering & ScienceCherenkov Radiation Cone Angle (theta_C) & Relativistic Threshold Kinetic Energy
Calculate the Cherenkov light-cone half-angle theta_C = DEGREES(ACOS(1 / (n * beta))) and minimum relativistic particle kinetic energy KE_min = m0_c2 * ((1 / SQRT(1 - 1 / n^2)) - 1) in water, ice, and glass.
Read the guide →EngineeringChezy Open-Channel Velocity, Critical Depth (y_c) & Specific Energy
Compute Chezy velocity for uniform flow, then explore rectangular-channel critical depth, minimum specific energy and Froude number using explicit SI inputs.
Read the guide →StatisticalChi-Square Goodness-of-Fit statistic formula: Observed vs Expected counts
Compute the Chi-Square Goodness-of-Fit test statistic SUMPRODUCT((O - E)^2 / E), degrees of freedom, and critical-value hypothesis decision.
Read the guide →StatisticalChi-Square Test of Independence: 2x2 contingency table and Phi effect size
Test whether two categorical variables are independent in a 2x2 table using N*(ad - bc)^2 / (R1*R2*C1*C2) and calculate expected counts and Phi.
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