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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 965 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 413 ÷ 22? (a) 2100 (b) 210 (c) 21
  2. 2.√34 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 5.7
  3. 3.Best estimate of 1948 ÷ 41? (a) 4900 (b) 490 (c) 49
  4. 4.Best estimate of 2022 ÷ 22? (a) 1010 (b) 101 (c) 10100
  5. 5.Best estimate of 2097 ÷ 38? (a) 52 (b) 520 (c) 5200
  6. 6.Best estimate of 1255 ÷ 22? (a) 6300 (b) 630 (c) 63
  7. 7.Best estimate of 1022 ÷ 72? (a) 150 (b) 1500 (c) 15
  8. 8.√77 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 9.0
  9. 9.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 9.3
  10. 10.√69 to 1 decimal place? (a) 8.1 (b) 8.4 (c) 8.3 (d) 8.2
  11. 11.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  12. 12.Best estimate of 4420 ÷ 66? (a) 63 (b) 6300 (c) 630
  13. 13.Best estimate of 2957 ÷ 32? (a) 990 (b) 9900 (c) 99
  14. 14.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.2
  15. 15.√31 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 5.6
  16. 16.Best estimate of 1304 ÷ 44? (a) 33 (b) 330 (c) 3300
  17. 17.√86 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  18. 18.Best estimate of 4807 ÷ 66? (a) 690 (b) 69 (c) 6900
  19. 19.√50 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.1 (d) 7.0
  20. 20.Best estimate of 2707 ÷ 73? (a) 3900 (b) 390 (c) 39
  21. 21.√41 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.6 (d) 6.5
  22. 22.Best estimate of 1416 ÷ 32? (a) 470 (b) 47 (c) 4700
  23. 23.Best estimate of 3309 ÷ 56? (a) 550 (b) 5500 (c) 55
  24. 24.√30 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.7
  25. 25.Best estimate of 2740 ÷ 74? (a) 390 (b) 3900 (c) 39
  26. 26.Best estimate of 4615 ÷ 67? (a) 6600 (b) 66 (c) 660
  27. 27.√29 to 1 decimal place? (a) 5.3 (b) 5.6 (c) 5.5 (d) 5.4
  28. 28.Best estimate of 2532 ÷ 36? (a) 63 (b) 630 (c) 6300
  29. 29.Best estimate of 742 ÷ 29? (a) 250 (b) 25 (c) 2500
  30. 30.Best estimate of 1864 ÷ 68? (a) 270 (b) 2700 (c) 27
  31. 31.Best estimate of 6186 ÷ 88? (a) 69 (b) 6900 (c) 690
  32. 32.Best estimate of 4068 ÷ 47? (a) 8100 (b) 810 (c) 81
  33. 33.Best estimate of 1592 ÷ 52? (a) 320 (b) 3200 (c) 32
  34. 34.√85 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  35. 35.Best estimate of 7095 ÷ 76? (a) 8900 (b) 890 (c) 89
  36. 36.Best estimate of 724 ÷ 38? (a) 1800 (b) 180 (c) 18
  37. 37.√72 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.5 (d) 8.8
  38. 38.Best estimate of 4599 ÷ 87? (a) 510 (b) 5100 (c) 51
  39. 39.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  40. 40.Best estimate of 693 ÷ 46? (a) 140 (b) 14 (c) 1400

Answer key

  1. 21
  2. 5.8
  3. 49
  4. 101
  5. 52
  6. 63
  7. 15
  8. 8.8
  9. 9.1
  10. 8.3
  11. 8.1
  12. 63
  13. 99
  14. 7.4
  15. 5.6
  16. 33
  17. 9.3
  18. 69
  19. 7.1
  20. 39
  21. 6.4
  22. 47
  23. 55
  24. 5.5
  25. 39
  26. 66
  27. 5.4
  28. 63
  29. 25
  30. 27
  31. 69
  32. 81
  33. 32
  34. 9.2
  35. 89
  36. 18
  37. 8.5
  38. 51
  39. 5.1
  40. 14

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