Steps

1. Identify the first non-zero digit — this is the first significant figure.
2. Count the required number of significant figures from the left.
3. Look at the digit immediately after the last significant figure.
4. If that digit is 5 or more, round up (add 1 to the last significant figure).
5. If it is less than 5, keep the last significant figure unchanged.
6. Replace all remaining digits with zeros (or remove them if decimal), keeping the decimal point in its original position.

Example 1: Round 37,846 to 2 significant figures

1. First significant figure: 3
2. Second significant figure: 7
3. The digit after 7 is 8 (5 or more), so round up: 7 → 8
4. Replace remaining digits with zeros

Answer: 38,000

Example 2: Round 0.004786 to 3 significant figures

1. First significant figure: 4
2. Second: 7 | Third: 8
3. The digit after 8 is 6 (5 or more), so round up: 8 → 9
4. Keep the leading zeros and remove the rest

Answer: 0.00479

Example 3: Round 560.089 to 4 significant figures

1. First: 5 | Second: 6 | Third: 0 | Fourth: 0
2. The digit after the fourth significant figure is 8 (5 or more), so round up: 0 → 1
3. Keep the decimal point and remove the remaining digits

Answer: 560.1

Sometimes we need to round a decimal number to a specific number of decimal places (d.p.) — that is, to a certain number of digits after the decimal point.

Steps

1. Identify the digit at the required decimal place.
2. Look at the digit immediately to the right of it.
3. If that digit is 5 or more, round up.
4. If it is less than 5, keep the digit unchanged.
5. Drop all digits to the right.

Example 1: Round 8.7659 to 2 decimal places

1. The second decimal place is 6.
2. The next digit is 5 (5 or more), so round up: 6 → 7.
3. Drop the remaining digits.

Answer: 8.77

Example 2: Round 3.14159 to 3 decimal places

1. The third decimal place is 1.
2. The next digit is 5 (5 or more), so round up: 1 → 2.

Answer: 3.142

Example 3: Round 0.24736 to 1 decimal place

1. The first decimal place is 2.
2. The next digit is 4 (less than 5), so keep 2 unchanged.

Answer: 0.2

In Tanzania, shopkeepers and traders frequently round prices when giving change or calculating totals. For example, if a customer buys items totalling TSh 2,847 and pays with TSh 3,000, the seller might round the change to the nearest hundred shillings (TSh 200) for simplicity. Similarly, when reporting monthly sales or calculating profit, a business owner may round financial figures to 2 significant figures to make the numbers easier to communicate and compare.