On the last day, the worker is paid $0.07*2²⁵ (it's by the power of 25 because it's 0 on the first day), which is $2,348,810.24. That means that the amount of money earned on all other days are $2,348,810.37, since 2⁰ + 2¹ + 2² + 2³... + 2ⁿ⁻² + 2ⁿ⁻¹ = 2ⁿ + 1.
That totals to approximately $4.6 million dollars, which is larger than $4 million.
