Rounding and estimating sums: Class 6 practice

What you should know first

• Place value

The idea behind rounding and estimating sums

Rounding replaces a number with a nearby 'friendly' value. Look at the digit to the right of the rounding place: 5 or more rounds up, less than 5 rounds down. Estimating a sum or product by rounding first helps check answers.

Step-by-step method

1. Choose the place to round to.
2. Look at the next digit to the right.
3. Round each number, then add or multiply.
4. Compare the estimate with the exact answer.

Worked example 1 (Basic)

Estimate 699 + 698 by rounding each number to the nearest 10.

1. 699 → 700
2. 698 → 700
3. Estimate = 700 + 700 = 1400
4. Exact sum 1397 for comparison
5. Answer: 1400

Worked example 2 (Standard)

Estimate 1253 + 5802 by rounding each number to the nearest 100.

1. 1253 → 1300
2. 5802 → 5800
3. Estimate = 1300 + 5800 = 7100
4. Exact sum 7055 for comparison
5. Answer: 7100

Worked example 3 (Challenge)

Estimate 55204 + 28430 by rounding each number to the nearest 1000.

1. 55204 → 55000
2. 28430 → 28000
3. Estimate = 55000 + 28000 = 83000
4. Exact sum 83634 for comparison
5. Answer: 83000

Common mistakes and misconceptions

• Looking at the wrong digit
• Rounding the final answer instead of each number when asked to estimate

Practice questions

1. (Basic) Estimate 168 + 958 by rounding each number to the nearest 10.
2. (Basic) Estimate 563 + 871 by rounding each number to the nearest 10.
3. (Standard) Estimate 3883 + 470 by rounding each number to the nearest 100.
4. (Standard) Estimate 3642 + 2380 by rounding each number to the nearest 100.
5. (Challenge) Estimate 86674 + 15962 by rounding each number to the nearest 1000.
6. (Challenge) Estimate 7654 + 49413 by rounding each number to the nearest 1000.

Answer key with full working

• Q1: 168 → 170 → 958 → 960 → Estimate = 170 + 960 = 1130 → Exact sum 1126 for comparison → Answer: 1130
• Q2: 563 → 560 → 871 → 870 → Estimate = 560 + 870 = 1430 → Exact sum 1434 for comparison → Answer: 1430
• Q3: 3883 → 3900 → 470 → 500 → Estimate = 3900 + 500 = 4400 → Exact sum 4353 for comparison → Answer: 4400
• Q4: 3642 → 3600 → 2380 → 2400 → Estimate = 3600 + 2400 = 6000 → Exact sum 6022 for comparison → Answer: 6000
• Q5: 86674 → 87000 → 15962 → 16000 → Estimate = 87000 + 16000 = 103000 → Exact sum 102636 for comparison → Answer: 103000
• Q6: 7654 → 8000 → 49413 → 49000 → Estimate = 8000 + 49000 = 57000 → Exact sum 57067 for comparison → Answer: 57000

Syllabus note

This skill is listed under "Knowing Our Numbers" for Class 6 in the NCERT/CBSE books. ICSE, IGCSE, IB and state boards may teach it in a different chapter or year.

Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.

Related practice and notes

• Knowing Our Numbers chapter notes (Class 6)
• Indian and international place value
• Roman numerals
• HCF and LCM by prime factorisation
• Adding and subtracting unlike fractions
• Unitary method word problems
• Perimeter and area of rectangles
• All Class 6 practice

Frequently asked questions

Which chapter is rounding and estimating sums in?

"Knowing Our Numbers", Class 6 Maths (NCERT/CBSE). Other boards may place it differently.

How were the answers checked?

Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.