A circle with a radius of 4 cm is carved out of a square piece of aluminium sheet with a 12 cm side. What is the size of the aluminium sheet that was left over?

Given, 

The radius of a circle = 4 cm

The side of a square sheet = 12 cm

Area of the square = side² 

= 12²

= 144 cm²

Area of the circle = πr²

 = 3.14 × 4² = 3.14 × 16

 = 50.24 cm²

Then, the Area of the remaining part = Area of an aluminium square sheet – the area of a circle

 = 144 – 50.24

= 93.76 cm²

Therefore, the area of the aluminium sheet that was left over is 93.76 cm².