That is correct, but you didn't post your thoughts about the exercise, so I can't know what you're thinking. (In future threads, please follow the guidelines, using the link provided in post #2.)
The
number of batteries purchased must reflect two things: It must be a multiple of 10 (because Marcus may purchase batteries only in packs of 10), and it must be a multiple of 6 (because Marcus does not want any batteries left over, after grouping the purchased batteries into sets of six).
There are many numbers that are common multiples of 6 and 10, but the exercise asks for the smallest one (30).
So the answer is, "The least number of battery packs that Marcus should buy is 30".
Here is a visual. Each square below is a battery. Each
row is a pack of ten batteries. Groups of six are shown in red.
1 Pack / 4 left over
■■■■■■ \(\quad\) ■■■■
2 Packs / 2 left over
■■■■■■ \(\quad\) ■■■■
■■■■■■ \(\quad\) ■■■■
3 Packs / 0 left over
■■■■■■ \(\quad\) ■■■■
■■■■■■ \(\quad\) ■■ \(\quad \; \quad\) ■■
■■■■■■ \(\quad\) \(\;\) \(\;\) \(\;\) \(\quad\) ■■■■
30 ÷ 6 = 5 sets of radio batteries
30 ÷ 10 = 3 battery packs
