Like many Indo-Aryan languages, Hindustani (Hindi-Urdu) has a decimal numeral system that is contracted to the extent that nearly every number 1–99 is irregular, and needs to be memorized as a separate numeral.^[1]

Numbers from 100 up are more regular. There are numerals for 100, sau; 1,000, hazār; and successive multiples by 100 of 1000: lākh (lakh) 100,000 (10⁵), karoṛ (crore) 1,00,00,000 (10⁷), arab 1,00,00,00,000 (10⁹, billion), kharab 1,00,00,00,00,000 (10¹¹), nīl 1,00,00,00,00,00,000 (10¹³), padma 1,00,00,00,00,00,00,000 (10¹⁵, quadrillion). (See Indian numbering system.) Lakh and crore are common enough to have entered Indian English.

For number 0, Modern Standard Hindi is more inclined towards śūnya (a Sanskrit tatsama) and Standard Urdu is more inclined towards sifr (borrowed from Arabic), while the native tadbhava-form is sunnā in Hindustani. Sometimes the ardha-tatsama form śūn is also used (semi-learned borrowing). Colloquially in Hinglish/Urdish, it is simply referred as jīro/zīro (from English zero).

In writing Hindi, numbers are usually represented using Devanagari numeral signs, while in Urdu the signs employed are those of a modified Eastern Arabic numeral system.