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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 591 · 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.√42 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  2. 2.Best estimate of 1683 ÷ 48? (a) 340 (b) 3400 (c) 34
  3. 3.Best estimate of 395 ÷ 32? (a) 13 (b) 130 (c) 1300
  4. 4.√94 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  5. 5.Best estimate of 1848 ÷ 31? (a) 6200 (b) 620 (c) 62
  6. 6.Best estimate of 1276 ÷ 87? (a) 1400 (b) 140 (c) 14
  7. 7.Best estimate of 3018 ÷ 69? (a) 43 (b) 4300 (c) 430
  8. 8.Best estimate of 4632 ÷ 82? (a) 580 (b) 58 (c) 5800
  9. 9.Best estimate of 2317 ÷ 42? (a) 580 (b) 58 (c) 5800
  10. 10.Best estimate of 3405 ÷ 52? (a) 6800 (b) 68 (c) 680
  11. 11.Best estimate of 1245 ÷ 27? (a) 42 (b) 4200 (c) 420
  12. 12.Best estimate of 791 ÷ 32? (a) 2600 (b) 260 (c) 26
  13. 13.Best estimate of 450 ÷ 29? (a) 1500 (b) 15 (c) 150
  14. 14.Best estimate of 4194 ÷ 47? (a) 8400 (b) 840 (c) 84
  15. 15.√32 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  16. 16.√80 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.9
  17. 17.Best estimate of 3185 ÷ 52? (a) 6400 (b) 64 (c) 640
  18. 18.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  19. 19.Best estimate of 3473 ÷ 63? (a) 58 (b) 5800 (c) 580
  20. 20.Best estimate of 6886 ÷ 81? (a) 86 (b) 860 (c) 8600
  21. 21.Best estimate of 3931 ÷ 77? (a) 490 (b) 49 (c) 4900
  22. 22.√22 to 1 decimal place? (a) 4.4 (b) 4.6 (c) 4.5 (d) 4.7
  23. 23.√26 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  24. 24.Best estimate of 2486 ÷ 64? (a) 410 (b) 41 (c) 4100
  25. 25.Best estimate of 1537 ÷ 29? (a) 5100 (b) 510 (c) 51
  26. 26.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 6.1
  27. 27.Best estimate of 2770 ÷ 37? (a) 690 (b) 69 (c) 6900
  28. 28.√50 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  29. 29.Best estimate of 2788 ÷ 73? (a) 4000 (b) 400 (c) 40
  30. 30.√71 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.6
  31. 31.Best estimate of 2866 ÷ 58? (a) 4800 (b) 48 (c) 480
  32. 32.Best estimate of 432 ÷ 26? (a) 1400 (b) 14 (c) 140
  33. 33.Best estimate of 2138 ÷ 71? (a) 310 (b) 3100 (c) 31
  34. 34.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.0 (d) 6.7
  35. 35.Best estimate of 5553 ÷ 58? (a) 930 (b) 93 (c) 9300
  36. 36.√37 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.3 (d) 6.1
  37. 37.Best estimate of 4117 ÷ 71? (a) 590 (b) 5900 (c) 59
  38. 38.Best estimate of 1068 ÷ 42? (a) 270 (b) 2700 (c) 27
  39. 39.√89 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  40. 40.Best estimate of 2420 ÷ 86? (a) 270 (b) 27 (c) 2700

Answer key

  1. 6.5
  2. 34
  3. 13
  4. 9.7
  5. 62
  6. 14
  7. 43
  8. 58
  9. 58
  10. 68
  11. 42
  12. 26
  13. 15
  14. 84
  15. 5.7
  16. 8.9
  17. 64
  18. 9.6
  19. 58
  20. 86
  21. 49
  22. 4.7
  23. 5.1
  24. 41
  25. 51
  26. 5.8
  27. 69
  28. 7.1
  29. 40
  30. 8.4
  31. 48
  32. 14
  33. 31
  34. 6.8
  35. 93
  36. 6.1
  37. 59
  38. 27
  39. 9.4
  40. 27

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