options: Fluently divide multi-digit numbers using the standard algorithm.

Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.

Find the greatest common factor of two whole numbers less than or equal to 100 and the least common multiple of two whole numbers less than or equal to 12. Use the distributive property to express a sum of two whole numbers 1–100 with a common factor as a multiple of a sum of two whole numbers with no common factor. For example, express 36 + 8 as 4 (9 + 2).
problem_activity: Task
Nina was finding multiples of 6. She said,
18 and 42 are both multiples of 6, and when I add them, I also get a multiple of 6: $$18+42 = 60.$$
Explain to Nina why adding two multiples of 6 will always result in another multiple of 6.


correct_option_index: 2