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Arithmetic & Number Sense

Overview

Operations, estimation, factors, multiples, and the numeric foundation for all other math.

Lessons

Understanding Place Value

Learn how the position of a digit determines its value — from ones and tens to millions and beyond, including reading and writing large numbers.

Comparing and Ordering Numbers

Use mathematical symbols to compare numbers and a number line to visualize their relationships — essential for everyday decisions.

Addition (Core Skills)

Master the column method and regrouping (carrying) to add multi-digit numbers accurately — the foundation of every budget and total.

Subtraction (Core Skills)

Find the difference between quantities using borrowing and regrouping — the core skill behind budgeting, change-making, and tracking what's left.

Multiplication Fundamentals

Discover how multiplication scales quantities efficiently — from bulk pricing and hourly wages to area calculations and beyond.

Division Fundamentals

Learn to split quantities equally, interpret remainders, and use long division — the math behind cost-per-unit, bill splitting, and resource allocation.

Understanding Fractions (Introduction)

Build a strong foundation by learning about numerators, denominators, and why a fraction is simply another way to write division.

Working with Decimals (Introduction)

Understand how decimal points extend place value into parts smaller than one — the foundation of money, measurement, and precise calculation.

Percentages and Conversions (Introduction)

Understand why percent means "per hundred" and master the conversions between fractions, decimals, and percentages.

Ratios and Proportions (Introduction)

Learn to compare two quantities using ratios and scale them up or down using proportions — the bridge from arithmetic to algebra.

Take the Arithmetic & Number Sense Quiz

Test your knowledge across all lessons — 25 or 50 questions, randomly drawn

Calculators

Arithmetic & Number Sense 3 Foundations Active

PEMDAS / Order of Operations Calculator

Evaluate numerical expressions following the correct order of operations: Parentheses, Exponents, Multiplication/Division, and Addition/Subtraction.

Proportion Solver

Solve for x in a proportion (two equal ratios) like a/b = c/d.

Place Value Explorer

Enter any whole number or decimal and see every digit broken down by place value — with expanded form and word form.

Number Comparator

Enter 2 to 6 numbers and compare them using <, >, and = — with ordering least to greatest and a visual number line.

Step-by-Step Arithmetic

Add, subtract, multiply, or divide two numbers and see the full column method with carrying, borrowing, and long division shown step by step.

Fraction Simplifier

Enter any fraction and instantly reduce it to lowest terms — with step-by-step work, decimal equivalent, and percentage.

Percent / Decimal / Fraction Converter

Enter a percent, decimal, or fraction and instantly convert it to all three forms — with step-by-step work showing exactly how each conversion is done.

Fraction Arithmetic

Add, subtract, multiply, or divide any two fractions with full step-by-step work — including LCD, cross-canceling, and simplification.

Rounding Calculator

Round any number to a chosen place value and see exactly where the rounding happens on the place value chart.