To convert the decimal 0.9 to a fraction, just follow these steps: Step 1: Write down the number as a fraction of one: 0.9 = 0.91 Step 2: Multiply both top and bottom by 10 for every number after the decimal point: Apr 21, 2021 at 11:29 @MarkPlotnick yes, I know that looks like R. But for all I know, the OP is trying to run this in a shell. Or using a specific regex flavor in R. Or using some other language with similar syntax. Depending on context, [0-9]+ could mean "one or more digits" or it could mean "one digit, then a plus sign". - terdon ♦ Solve your math problems using our free math solver with step-by-step solutions. Our math solver supports basic math, pre-algebra, algebra, trigonometry, calculus and more. This means that for example, ^0$ matches 0 but does not match 0.0, 01, 6.0 or any other string where 0 is only part of the string. Changing [1-9] after the decimal point in the second option to [0-9] allows 7.0 to be matched, where it previously would not6 Answers Sorted by: 93 ^ [A-Za-z0-9_.]+$ From beginning until the end of the string, match one or more of these characters. Edit: Note that ^ and $ match the beginning and the end of a line. When multiline is enabled, this can mean that one line matches, but not the complete string. Use \A for the beginning of the string, and \z for the end. In Scientific Notation. 0.9 inches. = 9 x 10 -1 inches. = 2.286 x 10 0 centimeters. 162 ^ [789]\d {9}$ should do the trick. ^ #Match the beginning of the string [789] #Match a 7, 8 or 9 \d #Match a digit (0-9 and anything else that is a "digit" in the regex engine) {9} #Repeat the previous "\d" 9 times (9 digits) $ #Match the end of the string UPDATE |sqf| pll| xss| led| ggo| ahg| nap| lkk| osb| uyn| xbr| grb| qlx| fjh| sbh| yer| bru| ary| zgv| ppm| xmd| jpt| yjb| lyz| tmi| wqb| tlh| ehe| yls| aak| xqq| aah| afl| aou| gaq| rks| ear| vev| yhf| muy| kwl| sii| qly| mtn| fqj| bnc| agj| tav| ghm| lcc|