If the youngest age is 7 years old, it is 7, 8, 9, 10, so the mantissa is 0, no, then it must be 6, 7, 8, 9. Look it up, and you can judge the answer by the mantissa.
Four people are continuous natural numbers, so 3024 is decomposed into prime factors, and 3024 = 2 * 2 * 2 * 3 * 3 * 7. Take the answers upstairs as a reference, at least seven of them are in it, so either 5678, 6789, 789 10, judging from the mantissa of the product.
2. Now, if these students let 1 people stay in the class and don't take part in labor, it is actually the least common multiple of 4, 6 and 7, 84, 84+ 1 = 85 people.