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Divisibility Test Calculator

Test a number against the divisors 2 to 12, the primes up to 100 or your own list — and see the mental rule and the working, not just yes or no.

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Chi-Square Test Calculatorχ² test of independence on any contingency table, showing observed, expected, the contribution and the standardised residual of every cell, plus Cramér's V. Cells with an expected count below 5 are flagged, because that is when the test stops being valid.F-Test CalculatorThree ways in: a one-way ANOVA from raw groups, a two-sample variance ratio, or a bare F with its two degrees of freedom. Each gives the p-value, the critical value at your α and the decision, from the same exact F distribution.Fisher's Exact Test CalculatorThe exact hypergeometric p for a 2×2 table — the right test when χ² fails on small counts. The two-tailed p sums every table at most as probable as the observed one, which is not the same as doubling the one-tailed p, and the odds ratio comes with its confidence interval.Kruskal-Wallis Test CalculatorThe rank-based alternative to ANOVA when the data are not normal. Shows the ranks assigned, each group's rank sum, H, df and p — with the tie correction applied, which matters as soon as two values are equal.Mann-Whitney U Test CalculatorCompares two independent samples without assuming normality. Gives U₁, U₂, the rank sums, and a z corrected for both continuity and ties — with the exact distribution used instead of the normal approximation while the samples are small enough for it to matter.Series Convergence Test CalculatorPick a series and see which test settles it — p-series, ratio, root, Leibniz, Cauchy condensation, limit comparison — with the limit it produces and whether the convergence is absolute or conditional.T-Test Calculator (Welch and Student)Paste two independent samples and get t, the degrees of freedom, the p-value, the critical value and the decision — computed BOTH ways, Welch and Student's pooled variance, with Welch as the default because it does not assume the two variances are equal. The Welch–Satterthwaite degrees of freedom are computed exactly, not rounded down. Sample means, standard deviations, the confidence interval of the difference and Cohen's d come with it.Amicable Number CheckerCheck whether two numbers are amicable — or give just one and get its candidate partner plus the verified loop, with perfect and sociable numbers identified.

Divisibility Test Calculator works straight from this page — free, instant, nothing to install. It sits under Numbers & arithmetic in our catalogue, alongside Chi-Square Test Calculator and F-Test Calculator.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Divisibility Test Calculator do?

Test a number against the divisors 2 to 12, the primes up to 100 or your own list — and see the mental rule and the working, not just yes or no.

When would I actually use this?

Reading a number written another way: a Roman numeral on a monument, a hexadecimal colour, a binary byte, or a fraction that needs reducing.

What is the most common mistake?

Assuming a decimal fraction survives a change of base. A tenth is exact in decimal and infinitely repeating in binary, which is why 0.1 + 0.2 is not 0.3 in most programming languages.

How is Divisibility Test Calculator different from Chi-Square Test Calculator?

They sit next to each other but answer different questions: Chi-Square Test Calculator is the one to open when you need it to χ² test of independence on any contingency table, showing observed, expected, the contribution and the standardised residual of every cell, plus Cramér's V. Cells with an expected count below 5 are flagged, because that is when the test stops being valid. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

F-Test Calculator is the closest one after this: Three ways in: a one-way ANOVA from raw groups, a two-sample variance ratio, or a bare F with its two degrees of freedom. Each gives the p-value, the critical value at your α and the decision, from the same exact F distribution.

What else is worth having open alongside it?

Fisher's Exact Test Calculator and Kruskal-Wallis Test Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Base conversion and number-theory results are exact. Roman numerals follow the standard subtractive form used since the Middle Ages, which is not the only one the Romans themselves used.

Further reading

All guides →
How-toHow to Round Numbers: Round Half Up, Round Half to Even, and MoreRound to any decimal place or number of significant figures, and learn when to use round half up versus round half to even to avoid bias.ExplainerSignificant Figures Explained: Counting, Rounding, and Why They MatterLearn what counts as a significant figure, the rules for leading, trailing, and captive zeros, and how sig figs keep your calculated answers honest.How-toHow to Find Prime Factors: Factor Trees and the Division MethodBreak any whole number into its prime building blocks with a factor tree or repeated division — and write the result as a clean prime factorization with exponents.How-toHow to Multiply and Divide Fractions: Multiply Across, Flip to DivideMultiplying fractions needs no common denominator — just multiply across. Dividing means multiplying by the reciprocal. Learn both with worked examples and how to simplify.How-toHow to Add and Subtract Fractions: Common Denominator, Combine, SimplifyYou can only add or subtract fractions that share a denominator. Learn to find a common denominator, combine the numerators, and simplify the result, with a worked example.How-toHow to Do Long Division: Divide, Multiply, Subtract, Bring DownLong division breaks a big division into a repeating four-step cycle. Learn the divide-multiply-subtract-bring-down loop and how to read the remainder, with a worked example.