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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 1 · 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.√71 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.7 (d) 8.5
  2. 2.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  3. 3.Best estimate of 2950 ÷ 43? (a) 740 (b) 7400 (c) 74
  4. 4.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  5. 5.√50 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.0 (d) 7.1
  6. 6.√51 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 7.3
  7. 7.Best estimate of 1422 ÷ 71? (a) 200 (b) 20 (c) 2000
  8. 8.Best estimate of 6683 ÷ 86? (a) 74 (b) 740 (c) 7400
  9. 9.√63 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  10. 10.Best estimate of 6782 ÷ 79? (a) 850 (b) 85 (c) 8500
  11. 11.√27 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.4 (d) 5.3
  12. 12.√85 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 9.2
  13. 13.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.1 (d) 5.0
  14. 14.Best estimate of 1175 ÷ 47? (a) 24 (b) 240 (c) 2400
  15. 15.√96 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  16. 16.Best estimate of 7430 ÷ 82? (a) 93 (b) 9300 (c) 930
  17. 17.√22 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.8 (d) 4.7
  18. 18.Best estimate of 3359 ÷ 69? (a) 4800 (b) 480 (c) 48
  19. 19.Best estimate of 934 ÷ 42? (a) 23 (b) 2300 (c) 230
  20. 20.Best estimate of 2131 ÷ 39? (a) 530 (b) 53 (c) 5300
  21. 21.√28 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  22. 22.Best estimate of 1718 ÷ 46? (a) 340 (b) 3400 (c) 34
  23. 23.√88 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.4 (d) 9.2
  24. 24.Best estimate of 3797 ÷ 41? (a) 950 (b) 9500 (c) 95
  25. 25.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  26. 26.Best estimate of 821 ÷ 43? (a) 2100 (b) 21 (c) 210
  27. 27.Best estimate of 3635 ÷ 38? (a) 910 (b) 9100 (c) 91
  28. 28.Best estimate of 1689 ÷ 56? (a) 2800 (b) 28 (c) 280
  29. 29.Best estimate of 1276 ÷ 47? (a) 260 (b) 2600 (c) 26
  30. 30.Best estimate of 1558 ÷ 26? (a) 5200 (b) 52 (c) 520
  31. 31.Best estimate of 4244 ÷ 52? (a) 8500 (b) 850 (c) 85
  32. 32.Best estimate of 1284 ÷ 38? (a) 3200 (b) 32 (c) 320
  33. 33.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.2 (d) 9.1
  34. 34.√87 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  35. 35.Best estimate of 1893 ÷ 26? (a) 63 (b) 630 (c) 6300
  36. 36.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  37. 37.Best estimate of 2341 ÷ 52? (a) 4700 (b) 470 (c) 47
  38. 38.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  39. 39.Best estimate of 4512 ÷ 64? (a) 7500 (b) 750 (c) 75
  40. 40.Best estimate of 2615 ÷ 37? (a) 6500 (b) 65 (c) 650

Answer key

  1. 8.4
  2. 6.1
  3. 74
  4. 9.9
  5. 7.1
  6. 7.1
  7. 20
  8. 74
  9. 7.9
  10. 85
  11. 5.2
  12. 9.2
  13. 4.8
  14. 24
  15. 9.8
  16. 93
  17. 4.7
  18. 48
  19. 23
  20. 53
  21. 5.3
  22. 34
  23. 9.4
  24. 95
  25. 5.6
  26. 21
  27. 91
  28. 28
  29. 26
  30. 52
  31. 85
  32. 32
  33. 8.9
  34. 9.3
  35. 63
  36. 9.7
  37. 47
  38. 9.1
  39. 75
  40. 65

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