As the other answer stated, the exponent is the number of times the decimal moves. If the decimal moves forward, the exponent is positive, and if the decimal moves backward, the exponent is negative.
-580,000 = -5.8 × 10^5
26,400,000 = 2.64 × 10^7
0.000135 = 1.35 × 10^-4
0.000002 = 2 × 10^-6
155,000,000 = 1.55 × 10^8
0.00000014 = 1.4 × 10^-7
0.0003 = 3 × 10^-4
7,800,000 = 7.8 × 10^6
0.0467 = 4.67 × 10^-2
3,500 = 3.5 × 10^3
900 = 9 × 10^2
1,000,000,000 = 1 × 10^9
The answer to the riddle is "In a hambulance".
Hope this helps!
~ V.