Please help i will mark brainly thank you

Answer:
Step-by-step explanation:
1 ==> 6.42 * 10^ -2
6.42 * 1/ 10 * 10
Answer =====> 0.0642
2: ====> 6.42 * 10^7
6.42 * 10000000
Answer ====> 642,00000
3: ======> 6.42 * 10^ -4
6.42 (1/1000)
Answer ====> 0.000642
4: =====> 6.42 * 10^5
6.42 * 100000
Answer =====> 642000
Hope that helps!!! :) -P-