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## I.D. Numbers 

Decimal notation is used for numbers, which denote either integer or real values. Any number can be preceded by a sign (+ or -); unsigned numbers cannot be signed. No comma may appear in a number. Real numbers are written with a decimal or scale factor or both. The letter E (or e) preceding the scale factor is pronounced as "times 10 to the power." Note that if a real number contains a decimal point, at least one digit must precede and follow the point. 

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Examples of unsigned numbers. 

3 03 6272844 0.6 5E-8 49.22E+08 1E10 

Incorrectly written numbers: 

3,487,159 3.487.159 XII 3. E10 5.E-16 five 

## I.E. Character Strings $^{.6 }$ 

Sequences of characters enclosed by apostrophes (single quote marks) are called strings. To include an apostrophe in a string, write the apostrophe twice. 

