How do I search a file using "less" for a value with a decimal point?

You can turn off regex mode by hitting Ctrl+R before typing the pattern:

          ^R     Don't interpret regular expression metacharacters; that is,
                 do a simple textual comparison.

/70\.5

will do the trick (inside less).

Two search expressions for numbers in less

/\.*[0-9]+\.*     # for numbers

/[0-9]*\.[0-9]+   # for numbers with a decimal part

Regex to search for numbers (with or without a decimal)

This regex works in less but also in other cases where the same regex syntax is used.

\.*[0-9]+\.*

You start the search engine with /, so if you want to find decimal numbers, but avoid text with dots (like file.txt) or periods between sentences, I think the following string is rather good,

/\.*[0-9]+\.*

Test file

There are several ways to use a dot. Here are some examples:

- 'Period' finishing a sentence
- Short for current directory or 'source' command in linux shells
- Separator between the name and extension of a file
- Separator in between the integer part and decimal part of a number
- Separator in special numerical or litteral strings (for example IP adress)

The following regex expression is rather simple and can identify
- numbers
- numerial strings

\.*[0-9]+\.*

.bashrc
hello-0
170.5
text.txt
170
170.
.551
asdf 170.5 qwerty
192.168.1.1
file.000
file.001

Regex to search for numbers with a decimal part

This regex works in less but also in other cases where the same regex syntax is used.

[0-9]*\.[0-9]+

The corresponding search command is

/[0-9]*\.[0-9]+

It will also find numerical strings (for example IP address), in general digits after a dot (including digits before the dot, if any).