If I had two turtles that are 45cm long and they need water how big will my cage be and the water must be 56 inches long?

To determine the size of the cage for your turtles, you need to consider both their length and the water requirement. Here's how you can calculate it:

1. Convert the length of the turtles from centimeters to inches, as the water requirement is given in inches. Since 1 inch = 2.54 centimeters, the length of each turtle in inches would be:
- Length of turtle in inches = Length of turtle in centimeters / 2.54

2. Calculate the total space required by adding the length of both turtles:
- Total space required = Length of turtle 1 + Length of turtle 2

3. Determine the cage size needed by adding the water requirement to the total space required:
- Cage size needed = Total space required + Water requirement

Let's plug in the numbers from your question to obtain the specific measurements:

Given:
- Length of each turtle = 45 cm
- Water requirement = 56 inches

1. Convert turtle length from cm to inches:
- Length of turtle in inches = 45 cm / 2.54 ≈ 17.72 inches

2. Calculate the total space required:
- Total space required = 17.72 inches + 17.72 inches = 35.44 inches

3. Determine the cage size needed by adding the water requirement:
- Cage size needed = 35.44 inches + 56 inches = 91.44 inches

Therefore, the cage for your turtles must be at least 91.44 inches long.