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Standard Form and Orders of Magnitude

The numbers 7,200,000,000 and 0.0000000072 contain almost the same significant digits but represent vastly different scales. Open Full Article...

Efficient Mental Calculation Strategies

Two different-looking calculations, 299 + 458 and 300 + 458 − 1, both equal 757. Open Full Article...

Prime Factors, Multiples and Divisibility

What makes 24 a factor of some numbers but a multiple of others? Open Full Article...

Place Value in Very Large and Very Small Numbers

Place value explains how a digit gains meaning from its position in a number. The same digit can represent a very large amount or a tiny fraction of one. Open Full Article...

Negative Numbers in Real-Life Contexts

A temperature of -3°C is warmer than -8°C because -3 is higher on the number line. Open Full Article...