To find how much the U.S. national debt increased from 1971 to 2021, we need to subtract the national debt in 1971 from the national debt in 2021.
The national debt in 2021 is given as \(2.9617 \times 10^{13}\) and in 1971 as \(3.98 \times 10^{11}\).
First, we can express both debts in a form that makes it easier to subtract:
- The debt in 1971: \[ 3.98 \times 10^{11} = 0.0398 \times 10^{13} \]
Now we can subtract: \[ \text{Increase in debt} = \text{Debt in 2021} - \text{Debt in 1971} \] \[ \text{Increase in debt} = (2.9617 \times 10^{13}) - (0.0398 \times 10^{13}) \] \[ = (2.9617 - 0.0398) \times 10^{13} \] \[ = 2.9219 \times 10^{13} \]
Thus, the national debt increased by \(2.9219 \times 10^{13}\).
The correct answer is:
- $2.9219 × 10^{13}