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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 421 · 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 1788 ÷ 84? (a) 2200 (b) 220 (c) 22
  2. 2.Best estimate of 1087 ÷ 21? (a) 540 (b) 54 (c) 5400
  3. 3.Best estimate of 3886 ÷ 72? (a) 56 (b) 560 (c) 5600
  4. 4.√66 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.0 (d) 8.1
  5. 5.Best estimate of 1380 ÷ 49? (a) 280 (b) 2800 (c) 28
  6. 6.Best estimate of 2143 ÷ 63? (a) 360 (b) 3600 (c) 36
  7. 7.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  8. 8.√61 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  9. 9.√34 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.6 (d) 5.9
  10. 10.Best estimate of 5048 ÷ 82? (a) 63 (b) 630 (c) 6300
  11. 11.Best estimate of 7432 ÷ 82? (a) 9300 (b) 930 (c) 93
  12. 12.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  13. 13.Best estimate of 1156 ÷ 28? (a) 3900 (b) 39 (c) 390
  14. 14.√65 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  15. 15.Best estimate of 2629 ÷ 79? (a) 3300 (b) 33 (c) 330
  16. 16.√90 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  17. 17.Best estimate of 972 ÷ 27? (a) 320 (b) 32 (c) 3200
  18. 18.Best estimate of 2640 ÷ 32? (a) 880 (b) 8800 (c) 88
  19. 19.Best estimate of 2238 ÷ 82? (a) 280 (b) 2800 (c) 28
  20. 20.Best estimate of 542 ÷ 39? (a) 14 (b) 1400 (c) 140
  21. 21.√31 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.5 (d) 5.6
  22. 22.Best estimate of 906 ÷ 61? (a) 150 (b) 1500 (c) 15
  23. 23.Best estimate of 1115 ÷ 63? (a) 1900 (b) 190 (c) 19
  24. 24.√85 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  25. 25.Best estimate of 1887 ÷ 21? (a) 9400 (b) 940 (c) 94
  26. 26.Best estimate of 926 ÷ 66? (a) 13 (b) 130 (c) 1300
  27. 27.Best estimate of 1827 ÷ 73? (a) 260 (b) 26 (c) 2600
  28. 28.Best estimate of 4531 ÷ 62? (a) 76 (b) 7600 (c) 760
  29. 29.Best estimate of 1097 ÷ 79? (a) 1400 (b) 14 (c) 140
  30. 30.Best estimate of 2191 ÷ 37? (a) 5500 (b) 55 (c) 550
  31. 31.Best estimate of 702 ÷ 32? (a) 2300 (b) 230 (c) 23
  32. 32.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  33. 33.Best estimate of 914 ÷ 29? (a) 30 (b) 300 (c) 3000
  34. 34.√89 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.2 (d) 9.4
  35. 35.√63 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.6 (d) 7.8
  36. 36.Best estimate of 7186 ÷ 87? (a) 800 (b) 80 (c) 8000
  37. 37.√88 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  38. 38.Best estimate of 933 ÷ 76? (a) 1200 (b) 120 (c) 12
  39. 39.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.5
  40. 40.Best estimate of 3252 ÷ 52? (a) 65 (b) 6500 (c) 650

Answer key

  1. 22
  2. 54
  3. 56
  4. 8.1
  5. 28
  6. 36
  7. 9.1
  8. 7.8
  9. 5.8
  10. 63
  11. 93
  12. 9.6
  13. 39
  14. 8.1
  15. 33
  16. 9.5
  17. 32
  18. 88
  19. 28
  20. 14
  21. 5.6
  22. 15
  23. 19
  24. 9.2
  25. 94
  26. 13
  27. 26
  28. 76
  29. 14
  30. 55
  31. 23
  32. 7.2
  33. 30
  34. 9.4
  35. 7.9
  36. 80
  37. 9.4
  38. 12
  39. 6.3
  40. 65

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