Tai Tham Tham Digit Zero
HTML Entity Browser Test:

U+1A90 is the Unicode hex value of the character Tai Tham Tham Digit Zero, which is categorized as "decimal digit number" in the Unicode 6.0 character table.

Unicode Character Information
Unicode Hex U+1A90
General Category Decimal Digit Number [Code: Nd]
Canonical Combining Class 0
Bidirectional Category L
Mirrored N
Unicode Character Encodings
Tai Tham Tham Digit Zero HTML Entity ᪐ (decimal entity), ᪐ (hex entity)
Windows Key Code Alt 6800 or Alt +1A901
Programming Source Code Encodings Python hex: u"\u1A90", Hex for C++ and Java: "\u1A90"
UTF-8 Hexadecimal Encoding 0xE1AA90
1 To type a Unicode symbol in Windows, hold down the ALT key and enter the decimal or hexadecimal code provided using the numeric keypad. The decimal alt code (Alt 6800) will only work on computers with support for this Unicode character in the active code page. The hexadecimal alt code (Alt +1A90) will work for all Unicode characters provided Hex input from the numeric keypad is enabled.
* If the Tai Tham Tham Digit Zero character does not display correctly in your browser, you may not have a Unicode font on your system that supports this particular symbol.