Unicode Trivia U+0B77

Codepoint: U+0B77 "ORIYA FRACTION THREE SIXTEENTHS"
Block: U+0B00..0B7F "Oriya"

The Odia language (formerly named Oriya) is spoken in Odisha (formerly Orissa): 

[source]

Unlike many Brahmic scripts, the head bar of each glyph is not a contiguous, straight line. As Omniglot says:

The Odia script developed from the Kalinga script, one of the many descendants of the Brahmi script of ancient India. The earliest known inscription in the Odia language, in the Kalinga script, dates from 1051.

The curved appearance of the Odia script is a result of the practice of writing on palm leaves, which have a tendency to tear if you use too many straight lines.

There are six "fractions signs" added to the "Oriya" block in Unicode 6.0 (October 2010):

• U+0B72 "୲" ORIYA FRACTION ONE QUARTER
• U+0B73 "୳" ORIYA FRACTION ONE HALF
• U+0B74 "୴" ORIYA FRACTION THREE QUARTERS
• U+0B75 "୵" ORIYA FRACTION ONE SIXTEENTH
• U+0B76 "୶" ORIYA FRACTION ONE EIGHTH
• U+0B77 "୷" ORIYA FRACTION THREE SIXTEENTHS

The original proposal by Anshuman Pandey explains that they were primarily used to subdivide one rupee into sixteen annas. See also Section 9.5 of South Asian Scripts-I (6.0).

Why does it stop at U+0B77 "ORIYA FRACTION THREE SIXTEENTHS"? It first glance, it looks like there must be some codepoints missing, but Anshuman Pandey explains that this is an additive base-4 system, where you can express "N/16" for N=1..15 with at most two of the above codepoints:

• 1/16 = "୵" = 1/16
• 2/16 = "୶" = 1/8
• 3/16 = "୷" = 3/16
• 4/16 = "୲" = 1/4
• 5/16 = "୲୵" = 1/4 + 1/16
• 6/16 = "୲୶" = 1/4 + 1/8
• 7/16 = "୲୷" = 1/4 + 3/16
• 8/16 = "୳" = 1/2
• 9/16 = "୳୵" = 1/2 + 1/16
• 10/16 = "୳୶" = 1/2 + 1/8
• 11/16 = "୳୷" = 1/2 + 3/16
• 12/16 = "୴" = 3/4
• 13/16 = "୴୵" = 3/4 + 1/16
• 14/16 = "୴୶" = 3/4 + 1/8
• 15/16 = "୴୷" = 3/4 + 3/16

As supporting evidence, he also includes a passage from "First Lessons in Oriya" by A. H. Young (1953, revised by B. Das. Cuttack: Orissa Mission Press):

The leading principle of Oriya arithmetic, to divide by four rather than any other number, pervades also the system of fractions.

This suggests base-4 was used elsewhere in the region's number system. I haven't been able to find any other concrete examples for Odia, but Kharosthi numbers have a base-4 component and most other Brahmic scripts have fractions built upon quarters or sixteenths, such as Bengali that we saw earlier.