Educators and K-12

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Readability Scores (Flesch-Kincaid) - Flesch-Kincaid Grade Level and Flesch Reading Ease for any text.
Statistics Quick-Read - Mean, median, mode, range, variance, and standard deviation (sample and population) for a list of numbers.
Quadratic Formula and Discriminant - Real or complex roots, discriminant sign, and vertex of the parabola for ax^2 + bx + c = 0.
Scientific Notation and Significant Figures - Convert any number to m * 10^n form; count significant figures from the input string.
Significant Figures (count + round) - Count sig figs in a number; round to a target N.
Genetic Codon Table (DNA / RNA) - Translate an in-frame DNA or RNA sequence to amino acids using the standard genetic code.
Number Base Converter (2-36) - Convert between any two integer bases from 2 to 36.
GPA Calculator (Weighted + Unweighted) - Standard US 4.0 / 5.0 GPA. One course per line: letter, credits, optional honors / AP track.
Confidence Interval (Proportion or Mean) - Wald z-interval for a sample proportion or a sample mean.
Sample Size for a Target Margin of Error - The inverse of the proportion confidence interval: the sample size n needed so a Wald margin of error meets a target.
System of Two Linear Equations - Solve a1*x + b1*y = c1; a2*x + b2*y = c2 via Cramer's rule.
Lexile Band by Grade (CCSS Stretch) - Grade-to-Lexile target ranges, K through 12.
Standards-Based Grade (Mastery 1-4) - Weighted overall mastery from per-standard levels (1-4) and optional major / supporting / additional priority.
Bell Curve / z-Score and Percentile - Where a value sits on a normal curve, as standard deviations from the mean and as a percentile.
Alternate Readability Formulas (SMOG / Coleman-Liau / Gunning Fog / ARI) - Four additional reading-grade formulas beyond Flesch-Kincaid.
Periodic Element Reference (Electronegativity / Configuration / Oxidation) - Per-element lookup: period, group, block, electronegativity, configuration, oxidation states.
Pearson Correlation (r, R^2, significance) - Pearson r and R^2 for paired x / y series.
Chi-Square Goodness-of-Fit - Chi-square = sum((observed - expected)^2 / expected) on k-1 df, the p-value from the chi-square CDF.
Linear Regression (slope, intercept, R^2) - Least-squares fitted line (slope, intercept), R^2, residual standard error, the slope t-test with a two-tailed p-value.
Grade-Curve Scaler - Flat-add, square-root, or linear rescale-to-target-mean grade curve, clamped to [0, 100].
Final-Exam Grade Needed - The score needed on the final to reach a target course grade, plus the maximum and minimum possible final grades.
Weighted Category Grade - Overall course percent and letter grade from a list of categories (percent and weight).
Two-Sample t-Test - Welch's two-sample t-statistic, Welch-Satterthwaite df, p-value, significance flag, and mean difference.
One-Sample t-Test (Mean vs Target) - The third member of the t-test family (with two-sample and paired).
One-Way ANOVA (Compare 3+ Group Means) - The member the t-test family was missing.
Chi-Square Test of Independence (Contingency Table) - Cross-tabulates two categorical variables (rows x columns) and tests whether they are associated.
Spearman Rank Correlation (rho) - The nonparametric companion to Pearson r that the correlation/regression family was missing.
Two-Proportion z-Test - The count-based member the hypothesis-test family was missing.
Paired (Dependent-Samples) t-Test - The matched-pairs companion the two-sample t-test set was missing.

Educators and K-12

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