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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 382 · 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 1268 ÷ 29? (a) 420 (b) 4200 (c) 42
  2. 2.Best estimate of 1042 ÷ 56? (a) 1700 (b) 170 (c) 17
  3. 3.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 5.8 (d) 6.0
  4. 4.√47 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.0 (d) 7.1
  5. 5.Best estimate of 1116 ÷ 73? (a) 1600 (b) 16 (c) 160
  6. 6.Best estimate of 845 ÷ 56? (a) 14 (b) 140 (c) 1400
  7. 7.Best estimate of 1545 ÷ 37? (a) 3900 (b) 39 (c) 390
  8. 8.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.9
  9. 9.√45 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.7 (d) 6.5
  10. 10.Best estimate of 1978 ÷ 49? (a) 400 (b) 4000 (c) 40
  11. 11.Best estimate of 2147 ÷ 49? (a) 4300 (b) 430 (c) 43
  12. 12.Best estimate of 3650 ÷ 42? (a) 9100 (b) 910 (c) 91
  13. 13.Best estimate of 1291 ÷ 21? (a) 65 (b) 6500 (c) 650
  14. 14.Best estimate of 1814 ÷ 52? (a) 36 (b) 3600 (c) 360
  15. 15.√41 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.3
  16. 16.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.3 (d) 6.4
  17. 17.Best estimate of 1762 ÷ 87? (a) 2000 (b) 20 (c) 200
  18. 18.√80 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.2 (d) 9.0
  19. 19.√72 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.6
  20. 20.Best estimate of 1147 ÷ 31? (a) 3800 (b) 380 (c) 38
  21. 21.Best estimate of 5219 ÷ 67? (a) 75 (b) 7500 (c) 750
  22. 22.√58 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.4 (d) 7.5
  23. 23.Best estimate of 1112 ÷ 44? (a) 28 (b) 280 (c) 2800
  24. 24.Best estimate of 4252 ÷ 58? (a) 710 (b) 7100 (c) 71
  25. 25.Best estimate of 433 ÷ 32? (a) 14 (b) 140 (c) 1400
  26. 26.Best estimate of 3295 ÷ 36? (a) 820 (b) 82 (c) 8200
  27. 27.Best estimate of 6397 ÷ 77? (a) 8000 (b) 800 (c) 80
  28. 28.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.6
  29. 29.Best estimate of 1608 ÷ 51? (a) 320 (b) 32 (c) 3200
  30. 30.√62 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.8 (d) 7.9
  31. 31.Best estimate of 1343 ÷ 47? (a) 27 (b) 2700 (c) 270
  32. 32.Best estimate of 2013 ÷ 23? (a) 1010 (b) 101 (c) 10100
  33. 33.Best estimate of 1003 ÷ 53? (a) 20 (b) 2000 (c) 200
  34. 34.√50 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.1 (d) 7.0
  35. 35.Best estimate of 6260 ÷ 89? (a) 700 (b) 7000 (c) 70
  36. 36.Best estimate of 425 ÷ 34? (a) 14 (b) 140 (c) 1400
  37. 37.√27 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.2 (d) 5.3
  38. 38.Best estimate of 2587 ÷ 27? (a) 86 (b) 860 (c) 8600
  39. 39.Best estimate of 1869 ÷ 86? (a) 210 (b) 2100 (c) 21
  40. 40.Best estimate of 1514 ÷ 52? (a) 30 (b) 300 (c) 3000

Answer key

  1. 42
  2. 17
  3. 5.8
  4. 6.9
  5. 16
  6. 14
  7. 39
  8. 5.7
  9. 6.7
  10. 40
  11. 43
  12. 91
  13. 65
  14. 36
  15. 6.4
  16. 6.6
  17. 20
  18. 8.9
  19. 8.5
  20. 38
  21. 75
  22. 7.6
  23. 28
  24. 71
  25. 14
  26. 82
  27. 80
  28. 7.4
  29. 32
  30. 7.9
  31. 27
  32. 101
  33. 20
  34. 7.1
  35. 70
  36. 14
  37. 5.2
  38. 86
  39. 21
  40. 30

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