# Standard Form

In science lessons, you have no doubt used scientific notation, or **standard form**, to write numerical answers to questions that are either very *large* or very *small*.

There are many confusions that arise when using this technique, so let's sort them out by beginning with the number **420**.

In standard form we re-write it in terms of *powers of ten*:

420 = 4.2 **× 10***²*

One important rule is that the number we are multiplying by ten must itself lie between 1 and 10:

NumberCorrect Standard FormIncorrect 5432 5·432 × 10^{3} 54·32 × 10^{2} 14,500 1·45 × 10^{4} 14·5 × 10^{3} *N.B. Values are however numerically correct!*

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