
Numeral systems are one of the highly endangered features of languages in today’s globalized world. Numeral systems of modern Indo-Aryan languages like Hindi, Gujarati, Bengali, Marathi., Punjabi etc. also are facing this threat with widespread use of English numbers in communicative domains. Young and children are increasingly switching to English numbers in their speech. This problem is compounded by relative irregularity of numeral systems in these languages. Because of their irregular morpho-syntax, numbers pose considerable challenge to native or 2nd language speakers trying to learn counting in these languages.
Hindi- Urdu has a decimal numeral system which is based on Sanskrit decimal numeral system i.e. employing 10 as the base and requiring 10 different numerals, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. In this system, units are uttered before tens. Even though based on Sanskrit, Hindi-Urdu numbers have gone irregular morphological change over time, making them look very different from the originals.
Cardinal numbers in Hindi-Urdu from 1 to 100 can be seen in the following table :

Based on the above table of numbers, we can deduce the various allomorphs (i.e. complementary morphs which manifest a morpheme in its different phonological or morphological environments) available in Hindi-Urdu.
1 [ek] = gyā (ग्या), ik (इक), ika (इकअ), ikyā (इक्या)
2 [do] = bā (बा), ba (ब), by (बय)
3 [tīn] = te (ते), taĩ (तैं), ti (ति), tir (तिर)
4 [cār] = cau (चौ), ca (च), caũ (चौं), caur (चौर)
5 [pānc] = pand (पंद), pac (पच), paĩ (पैं)
6 [che] = so (सो), cha (छ), chi (छि), chiyā (छिया)
7 [sāt] = sat (सत), sattā (सत्ता), saĩ (सैं), saŗ (सड़)
8 [ āṭh] = aṭhā (अठा), aṭṭhā (अट्ठा), aŗ (अड़), aṭha (अठ)
9 [nau] = un (उन), unn (उन्न), nav (नव)
10 [das] = rah (रह), dah (दह), lah (लह)
20 [bīs] = īs (ईस)
40 [cālīs] = āllīs (आलीस), tālīs (तालीस)
50 [pacās] = van (वन), pan (पन), ppan (प्पन)
60 [sāṭh] = saṭh (सठ)
70 [sattar] = hattar (हत्तर)
80 [assī] = āsī (आसी), yāsī (यासी)
90 [nabbe] = ānve (आनवे)