**Question:**

The numbers 2.745 and 2.735 on rounding off to 3 significant figures will give

(a) 2.75 and 2.74

(b) 2.74 and 2.73

(c) 2.75 and 2.73

(d) 2.74 and 2.74

**Solution:**

(d)

Key concept: While rounding off measurements, we use the following rules by convention:

1. If the digit to be dropped is less than 5, then the preceding digit is left unchanged.

2. If the digit to be dropped is more than 5, then the preceding digit is raised by one.

3. If the digit to be dropped is 5 followed by digits other than zero, then the preceding digit is raised by one.

4. If digit to be dropped is 5 or 5 followed by zeros, then preceding digit is left unchanged, if it is even.

5. If digit to be dropped is 5 or 5 followed by zeros, then the preceding digit is raised by one, if it is odd.

Units and Measurements

Let us round off 2.745 to 3 significant figures.

Here the digit to be dropped is 5, then preceding digit is left unchanged, if it is even.

Hence on rounding off 2.745, it would be 2.74.

Now consider 2.737, here also the digit to be dropped is 5, then the preceding digit is raised by one, if it is odd. Hence on rounding off 2.735 to 3

significant figures, it would be 2.74.