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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 832 · 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 2421 ÷ 38? (a) 6100 (b) 61 (c) 610
  2. 2.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  3. 3.Best estimate of 2063 ÷ 69? (a) 290 (b) 29 (c) 2900
  4. 4.Best estimate of 4721 ÷ 78? (a) 5900 (b) 590 (c) 59
  5. 5.Best estimate of 832 ÷ 44? (a) 21 (b) 210 (c) 2100
  6. 6.√59 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  7. 7.Best estimate of 763 ÷ 41? (a) 1900 (b) 190 (c) 19
  8. 8.Best estimate of 1388 ÷ 37? (a) 350 (b) 35 (c) 3500
  9. 9.Best estimate of 2353 ÷ 26? (a) 78 (b) 7800 (c) 780
  10. 10.√43 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.5 (d) 6.6
  11. 11.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.2 (d) 7.1
  12. 12.√41 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.5
  13. 13.Best estimate of 2469 ÷ 56? (a) 4100 (b) 410 (c) 41
  14. 14.√20 to 1 decimal place? (a) 4.4 (b) 4.6 (c) 4.3 (d) 4.5
  15. 15.Best estimate of 635 ÷ 44? (a) 160 (b) 1600 (c) 16
  16. 16.Best estimate of 1716 ÷ 21? (a) 8600 (b) 860 (c) 86
  17. 17.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.0 (d) 8.2
  18. 18.Best estimate of 4800 ÷ 89? (a) 5300 (b) 53 (c) 530
  19. 19.Best estimate of 3038 ÷ 88? (a) 340 (b) 3400 (c) 34
  20. 20.Best estimate of 1959 ÷ 69? (a) 28 (b) 280 (c) 2800
  21. 21.Best estimate of 2617 ÷ 86? (a) 29 (b) 290 (c) 2900
  22. 22.Best estimate of 3455 ÷ 42? (a) 86 (b) 860 (c) 8600
  23. 23.Best estimate of 6450 ÷ 69? (a) 920 (b) 92 (c) 9200
  24. 24.√82 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 9.3
  25. 25.Best estimate of 760 ÷ 28? (a) 25 (b) 250 (c) 2500
  26. 26.√79 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 9.0
  27. 27.√45 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 6.7
  28. 28.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 5.9
  29. 29.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 5.2
  30. 30.Best estimate of 1256 ÷ 31? (a) 420 (b) 42 (c) 4200
  31. 31.Best estimate of 1166 ÷ 73? (a) 17 (b) 1700 (c) 170
  32. 32.Best estimate of 844 ÷ 26? (a) 28 (b) 2800 (c) 280
  33. 33.Best estimate of 3889 ÷ 68? (a) 560 (b) 56 (c) 5600
  34. 34.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  35. 35.Best estimate of 490 ÷ 39? (a) 120 (b) 1200 (c) 12
  36. 36.Best estimate of 918 ÷ 26? (a) 3100 (b) 31 (c) 310
  37. 37.Best estimate of 694 ÷ 28? (a) 230 (b) 23 (c) 2300
  38. 38.Best estimate of 2425 ÷ 69? (a) 35 (b) 350 (c) 3500
  39. 39.Best estimate of 3445 ÷ 69? (a) 49 (b) 490 (c) 4900
  40. 40.√86 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.3 (d) 9.4

Answer key

  1. 61
  2. 5.8
  3. 29
  4. 59
  5. 21
  6. 7.7
  7. 19
  8. 35
  9. 78
  10. 6.6
  11. 7.3
  12. 6.4
  13. 41
  14. 4.5
  15. 16
  16. 86
  17. 8.1
  18. 53
  19. 34
  20. 28
  21. 29
  22. 86
  23. 92
  24. 9.1
  25. 25
  26. 8.9
  27. 6.7
  28. 6.1
  29. 4.9
  30. 42
  31. 17
  32. 28
  33. 56
  34. 7.4
  35. 12
  36. 31
  37. 23
  38. 35
  39. 49
  40. 9.3

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