Digital image problem 1

First problem: 

Think you want to print out a photograph with a size of DIN A4: 210 × 297 mm

maintaining a printing quality of 200 dpi. Which resolution would the image need?

To find the required image resolution:

Step 1: Convert A4 dimensions from millimeters to inches.
1 inch = 25.4 mm

• Width: $210 \div 25.4 \approx 8.27$ in

• Height: $297 \div 25.4 \approx 11.69$ in

Step 2: Multiply by desired print DPI (200 dpi).

• Width: $8.27 \times 200 \approx 1654$ pixels

• Height: $11.69 \times 200 \approx 2338$ pixels

  Required resolution at 200 dpi: 

• 1654 × 2339 pixels