Understanding the Four Ratios Used in Islamic Inheritance Calculations

⚖️ Ratio of Numbers in Inheritance (Warāthah)
Excerpt from the book “Islami Qanun-e-Warāthah” by Maulana Abu Nu’man Basheer Ahmad


❖ Understanding Ratios in Inheritance Calculations​


When there are multiple fixed-share heirs (Aṣḥāb al-Furūḍ) in a case of inheritance, the number for rectifying the problem (ʿadad al-taṣḥīḥ) is determined using the four types of numerical ratios, known as:


Tamāthul (تماثل)
Tadākhul (تداخل)
Tawāfuq (توافق)
Tabāyun (تباین)


➊ Tamāthul (Equality)​


When two numbers are equal, the relationship is called Tamāthul.
Example: 3 : 3
In such cases, any one of the numbers can be taken as the base of the problem.
Example: If the heirs are a husband and a sister, both receive ½, so the base number becomes 2.


Tadākhul (Inclusiveness / Direct Divisibility)


When one number is smaller and divides the larger exactly, this is called Tadākhul.
Example: 6 : 3
Here, the larger number becomes the base.
Example: If the heirs are a mother and a maternal brother, with shares of ⅓ and ⅙ respectively, then since 6 : 3 is a case of Tadākhul, the base number is 6.


➌ Tawāfuq (Agreement)​


When one number is smaller, and does not divide the larger, but there exists a third number that divides both, the ratio is called Tawāfuq.
Example: 8 : 6 (common divisor is 2)


In such cases, use the Wifq (accordance):


  • Multiply the wifq of one number by the total of the other.

Example:
Heirs: Husband, Mother, Three Sons, and One Daughter


  • Husband: ¼
  • Mother: ⅙
  • Children: remainder (boys and girl as aṣabah)

→ Between 6 (mother’s base) and 4 (husband’s base), the ratio is Tawāfuq.


  • Wifq of 6 is 3, wifq of 4 is 2.
  • Multiply: 3 × 4 = 12 or 2 × 6 = 12
    Base number becomes 12

Tabāyun (Complete Difference)


When neither number divides the other, nor is there a common divisor, the ratio is Tabāyun.
Example: 9 : 7


Here, multiply both numbers together to find the base.


Example:
Heirs: Husband, Mother, and Brother


  • Husband: ½
  • Mother: ⅓
  • Brother: ʿAṣabah
    → 3 : 2 is Tabāyun
  • Multiply: 3 × 2 = 6
    Base number becomes 6

❖ Summary Table of Ratios:

Ratio TypeDefinitionExampleMethod for Finding Base Number
TamāthulEqual Numbers3:3Take either number
TadākhulSmaller divides larger6:3Use the larger number
TawāfuqCommon divisor exists8:6Multiply wifq × total of other
TabāyunNo common divisor9:7Multiply both numbers

 
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