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The Num lock should always be enabled. If it is disabled when you are attempting an alt code, it may cause errors or unexpected results in some applications. For example, Alt+4 could be interpreted as Alt +, ← which causes the browser to go back if the Num lock is disabled.
If your laptop keyboard doesn't have a separate NumPad, you should hold FN button with Alt button while typing the code.
This method does not work for Linux system, but it is possible to use Unicode.

Less than Symbol

Less-than symbol < is a mathematical operator indicates the inequality between two values or two numbers. less-than is formed of two lines equal in length and joining at an acute angle opening to the right. It is generally placed between two values signaling that the first value is less than the second value.

Many programming languages like C++ use the less-than sign in ColdFusion, Fortran, and Bourne shell.

The doubles less-than sign≪ means an approximation of much-less-than sign. In C++ and c languages it indicates a binary left shift and output stream in C++; in Ruby framework, it is used to append an element to an array.

How to use and type Less than symbol code?

If your keyboard contains separate NumPad, you should be sure that it is enabled. If it is not, press the Num Lock key to activate it then press hold down the Alt key on the left side. Type the number that represents that character or the symbol you want to insert and then release the insert key.
For example, for the greek letter omega Ω press and hold Alt and the type 0234 and then release.
There is another method that works only for word documents. In this method, you should type the characters first then press Alt and X. For example ( 0234 + Alt + X for greek letter omega ).
If you have a keyboard that doesn't have NumPad here is what will work for you. Find the Function key ( FN ) then presses and hold the function key while holding press and release Num LK key; then release FN key. This method will activate the numeric keypad in your laptop.
Then do the same steps as in the previous example.
Notice that in IBM code you don't use 0 (Alt + 255 ) before the code which is different from the windows generator that requires to add 0 (Alt + 0255 ) before the code.

Table of Symbols and Codes

Symbol	Title / Description	Unicode	Code / HTML Code
⪅	Less-than Or Approximate	⪅	⪅
﹤	Small Less-than	﹤	﹤
≮	Not Less-than	≮	≮
⪨	Less-than Closed By Curve Above Slanted Equal	⪨	⪨
⪁	Less-than Or Slanted Equal To With Dot Above	⪁	⪁
⥶	Less-than Above Leftwards Arrow	⥶	⥶
≨	Less-than But Not Equal To	≨	≨
≦	Less-than Over Equal To	≦	≦
⥷	Leftwards Arrow Through Less-than	⥷	⥷
⪦	Less-than Closed By Curve	⪦	⪦
⍃	Apl Functional Symbol Quad Less-than	⍃	⍃
≪	Much Less-than	≪	≪
≤	Less-than Or Equal To	≤	≤
⩿	Less-than Or Slanted Equal To With Dot Inside	⩿	⩿
⪛	Double-line Slanted Equal To Or Less-than	⪛	⪛
⋘	Very Much Less-than	⋘	⋘
⪍	Less-than Above Similar Or Equal	⪍	⪍
⋦	Less-than But Not Equivalent To	⋦	⋦
⫷	Triple Nested Less-than	⫷	⫷
⪙	Double-line Equal To Or Less-than	⪙	⪙
⋜	Equal To Or Less-than	⋜	⋜
⪝	Similar Or Less-than	⪝	⪝
⪣	Double Nested Less-than With Underbar	⪣	⪣
⋖	Less-than With Dot	⋖	⋖
⧀	Circled Less-than	⧀	⧀
⪡	Double Nested Less-than	⪡	⪡
⪃	Less-than Or Slanted Equal To With Dot Above Right	⪃	⪃
⩽	Less-than Or Slanted Equal To	⩽	⩽
＜	Fullwidth Less-than	＜	＜
⩻	Less-than With Question Mark Above	⩻	⩻
⪕	Slanted Equal To Or Less-than	⪕	⪕
≴	Neither Less-than Nor Equivalent To	≴	≴
≰	Neither Less-than Nor Equal To	≰	≰
⫹	Double-line Slanted Less-than Or Equal To	⫹	⫹
≲	Less-than Or Equivalent To	≲	≲
⩹	Less-than With Circle Inside	⩹	⩹
⪟	Similar Above Less-than Above Equals	⪟	⪟
⪉	Less-than And Not Approximate	⪉	⪉
⪗	Slanted Equal To Or Less-than With Dot Inside	⪗	⪗
⪇	Less-than And Single-line Not Equal To	⪇	⪇
<	Less-than	<	<