Final answer:
The number that cannot be divided into 3 groups without a remainder is 326.
Step-by-step explanation:
In order to determine which number cannot be divided into 3 groups without a remainder, we need to divide each number by 3 and check for remainders. If a number has a remainder when divided by 3, it cannot be divided into 3 groups without a remainder.
- 326 divided by 3 is 108 with a remainder of 2.
- 432 divided by 3 is 144 with a remainder of 0.
- 537 divided by 3 is 179 with a remainder of 0.
- 663 divided by 3 is 221 with a remainder of 0.
Therefore, the number that cannot be divided into 3 groups without a remainder is 326.