The word Day occurs 365 times in Quran

Total occurrences of the word day (root: ya-waw-mim) in all forms  
Ocurrences of plural forms:  

yawmayni (2:203, 41:9, 41:12)
3
  

l-ayamu (3:140)
1
  

ayyamin (2:184, 2:185, 2:196, 2:203, 3:41, 5:89, 7:54, 10:3, 11:7, 11:65, 22:28, 25:59, 32:4, 41:10, 41:16, 50:38, 57:4, 69:7)
18
  

ayyami (10:102)
1
  

bi-ayyami (14:5)
1
  

l-ayami (69:24)
1
  

wa-ayyaman (34:18)
1
  

ayyaman (2:80)
1
  

ayyama (45:14)
1
  

ayyaman (2:184)
1
  

ayyaman (3:24)
1
  
Occurrences with suffixes (e.g., yawmikum, yawmihim), referring to possessive forms like “their day” or “your day”  

yawmaku (21:103)
1
  

yawmikum (6:130, 32:14, 39:71, 45:34)
4
  

yawmihim (7:51)
1
  

yawmihimu (51:60)
1
  

yawmahumu (43:83, 52:45, 70:42)
3
  
Occurrence of singular form: 405 – 30 – 10  
365