Which number is completely divisible by 99?

Given data

• Divisible by 99 means divisible by 9 and by 11.

Checks

2178: digit sum = 2+1+7+8 = 18 ⇒ divisible by 9; 11 test: (2 − 1 + 7 − 8) = 0 ⇒ divisible by 11 ⇒ divisible by 99.1452: digit sum = 12 (not a multiple of 9) ⇒ not by 9 ⇒ not by 99.1364: digit sum = 14 ⇒ not by 9.1639: digit sum = 19 ⇒ not by 9.

Final Answer

Number divisible by 99: 2178.