Math

Build numbers from 0 to 99 with tens and ones. Link the numeral, counters, and base-ten blocks, and explore regrouping ten ones as one ten.

Free online cylinder calculator. Enter the radius and height to quickly find the base area, lateral area, total surface area, and volume of any cylinder.

Quickly convert voltage units like volts, millivolts, and kilovolts online with support for batch calculations.

Calculate the difference of cubes (a³-b³) instantly. Supports integers and decimals, ideal for math learning and algebra.

Quickly calculate the sum of cubes for integer sequences. Supports custom number lists or continuous ranges for math and engineering.

Advanced scientific calculator supporting complex math operations and function calculations.

Split a teen number into ten and extra ones. Subtract from the ten-frame, then combine the remaining counters to find the difference.

Accurately calculate the volume and weight of mulch needed for landscaping and paving to avoid material waste and optimize costs.

Quickly convert illuminance units including lux (lx), foot-candles (fc), and phots (ph).

Quickly and accurately convert between different torque units, including common units like Newton-meters and foot-pounds.

A curated collection of frequently used phone numbers for couriers, banks, telecom providers, and government services. Search and copy in seconds—find the right number fast.

Quickly estimate how many litres and cans of paint you need based on room dimensions, door and window areas, paint coverage, and number of coats.

Input two sets of continuous data, quickly calculate Pearson correlation coefficient R, and determine the strength of linear correlation.

Enter the variance and sample size of two datasets to quickly calculate the F-statistic and p-value, and determine if the variances are significantly different.

Create elementary math worksheets for length, weight, time, and area conversions. Customize the difficulty and layout, then export and print.

Explore subtraction by first reaching ten, then subtracting the remainder. Adjust the numbers and follow the counters and equation step by step.

Create customizable make-a-ten addition worksheets for early elementary students, with flexible question counts and layouts.

Connect groups of counters to addition and subtraction equations. Choose an answer, reveal hints, and check each picture-based problem.

Estimate your risk of type 2 diabetes using age, BMI, waist circumference, blood pressure, and family history. Get an initial screening recommendation.

Explore rectangular prisms, cubes, cylinders, and spheres. Predict rolling behavior and click matching objects in an illustrated classroom scene.