1.2x10^4
Explanation:
2.
negative exponent means it's a fraction so
4.5x10^-3 is 1/4500 or 0.0045 so
it's a very small number
1.
^4 means means move the decimal 4 spots
12×10^4 = 12,000
3.
^3 means move the decimal 3 spots
3.8 x 10^3 =
3800
4.
7.5x10^3 =
7500