10. 3 × 10² + 5 × 10⁴ + 7 × 10⁵ =

Решаем по действиям:

1. 10² = 10 × 10 = 100
2. 10⁴ = 10 × 10 × 10 × 10 = 10000
3. 10⁵ = 10 × 10 × 10 × 10 × 10 = 100000
4. 3 × 100 = 300
5. 5 × 10000 = 50000
6. 7 × 100000 = 700000
7. 300 + 50000 + 700000 = 750300

Ответ: 750300