A number is divisible by 3, if the sum of the digits is divisible by 3
METHOD
Step 1. Add up the digits of the given number
Step 2. If the sum of the digits is divisible by 3, then the number is also divisible by 3.
Example 1. Consider the number 378
Step 1. 3 + 7 + 8 = 18
Step 2. 18 / 3 = 6
Since the sum of the digits is divisible by 3, so 378 is divisible by 3.
Check. 378 / 3 = 84 exactly
Example 2. Consider the number 427
Step 1. 4 + 2 + 7 = 13
Step 2. 13 / 3 = 4 remain 1
Since the sum of the digits is not divisible by 3, so 427 is not divisible by 3.
Check. 427 / 3 = 142 remain 1
Example 3. Consider the number 8253
Step 1. 8 + 2 + 5 + 3 = 18
Step 2. 18 / 3 = 6
Since the sum of the digits is divisible by 3, so 8253 is divisible by 3.
Check. 8253 / 3 = 2751 exactly
Example 4. Consider the number 20872
Step 1 2 + 0 + 8 + 7 + 2 = 19
Step 2. 19 / 3 = 6 remain 1
Since the sum of the digits is not divisible by 3, so 427 is not divisible by 3.
Check.20872 / 3 = 6957 remain 1
| Number | Step 1 | Step 2 | Step 2 Divisible by 3? | Number Divisible by 3? |
|---|---|---|---|---|
| 378 | 3 + 7 + 8 = 18 | 18 / 3 = 6 exactly | Yes | Yes |
| 427 | 4 + 2 + 7 = 13 | 13 / 3 = 4 remain 1 | No | No |
| 8253 | 8 + 2 + 5 + 3 = 18 | 18 / 3 = 6 exactly | Yes | Yes |
| 20872 | 2 + 0 + 8 + 7 + 2 = 19 | 19 / 3 = 6 remain 1 | No | No |
