Rounding off to the nearest 10:

To round off a number to the nearest 10, we look at the ones digit. If the ones digit is 0, 1, 2, 3, or 4, we round down to the previous ten. If the ones digit is 5, 6, 7, 8, or 9, we round up to the next ten.

Let's round off the given numbers to the nearest 10:

1. 1378:
- The ones digit is 8, which is greater than 5.
- So, we round up to the next ten, which is 1380.

2. 2549:
- The ones digit is 9, which is greater than 5.
- So, we round up to the next ten, which is 2550.

3. 3180:
- The ones digit is 0, which is less than 5.
- So, we round down to the previous ten, which is 3180.

4. 3905:
- The ones digit is 5, which is exactly 5.
- In this case, we look at the tens digit. If it is even, we round down; if it is odd, we round up.
- The tens digit is 0, which is even.
- So, we round down to the previous ten, which is 3900.

Rounding off to the nearest hundred:

To round off a number to the nearest hundred, we look at the tens digit. If the tens digit is 0, 1, 2, 3, or 4, we round down to the previous hundred. If the tens digit is 5, 6, 7, 8, or 9, we round up to the next hundred.

Let's round off the given numbers to the nearest hundred:

1. 1378:
- The tens digit is 7, which is greater than 5.
- So, we round up to the next hundred, which is 1400.

2. 2549:
- The tens digit is 4, which is less than 5.
- So, we round down to the previous hundred, which is 2500.

3. 3180:
- The tens digit is 8, which is greater than 5.
- So, we round up to the next hundred, which is 3200.

4. 3905:
- The tens digit is 0, which is less than 5.
- So, we round down to the previous hundred, which is 3900.

Rounding off to the nearest thousand:

To round off a number to the nearest thousand, we look at the hundreds digit. If the hundreds digit is 0, 1, 2, 3, or 4, we round down to the previous thousand. If the hundreds digit is 5, 6, 7, 8, or 9, we round up to the next thousand.

Let's round off the given numbers to the nearest thousand:

1. 1378:
- The hundreds digit is 3, which is less than 5.
- So, we round down to the previous thousand, which is 1000.