1:0,25 0,6:0,15

To add and multiply decimal numbers, follow these steps:

1. Write the numbers vertically, aligning the decimal points.

   1 0.25

• 0.6 0.15

2. Start from the rightmost column (the ones place) and move left, adding or multiplying each corresponding pair of numbers. Carry any extra digits leftward when necessary.

   1 0.25

• 0.6 0.15

1.6 0.40

So, 1 + 0.6 = 1.6 and 0.25 + 0.15 = 0.40.