Compare 4.2×10^6 and 6.5×10^3. What is the exponent of the lesser number?

To compare the two numbers, we can compare the exponents. The exponent of 4.2×10^6 is 6, and the exponent of 6.5×10^3 is 3. Since 3 is less than 6, the exponent of the lesser number is 3.