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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 385 · 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 1233 ÷ 33? (a) 410 (b) 4100 (c) 41
  2. 2.Best estimate of 3614 ÷ 52? (a) 720 (b) 72 (c) 7200
  3. 3.Best estimate of 5425 ÷ 62? (a) 900 (b) 9000 (c) 90
  4. 4.√24 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 4.6
  5. 5.Best estimate of 4768 ÷ 76? (a) 60 (b) 600 (c) 6000
  6. 6.Best estimate of 2088 ÷ 64? (a) 3500 (b) 350 (c) 35
  7. 7.√34 to 1 decimal place? (a) 5.7 (b) 6.0 (c) 5.9 (d) 5.8
  8. 8.Best estimate of 1347 ÷ 57? (a) 22 (b) 220 (c) 2200
  9. 9.√42 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.6
  10. 10.√23 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.5 (d) 4.7
  11. 11.Best estimate of 1311 ÷ 39? (a) 3300 (b) 330 (c) 33
  12. 12.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  13. 13.Best estimate of 1239 ÷ 24? (a) 6200 (b) 62 (c) 620
  14. 14.Best estimate of 1547 ÷ 32? (a) 520 (b) 5200 (c) 52
  15. 15.√59 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8
  16. 16.√76 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  17. 17.Best estimate of 1247 ÷ 39? (a) 310 (b) 3100 (c) 31
  18. 18.Best estimate of 3297 ÷ 64? (a) 550 (b) 55 (c) 5500
  19. 19.Best estimate of 2688 ÷ 36? (a) 670 (b) 6700 (c) 67
  20. 20.Best estimate of 832 ÷ 33? (a) 28 (b) 280 (c) 2800
  21. 21.Best estimate of 1455 ÷ 71? (a) 210 (b) 2100 (c) 21
  22. 22.√87 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  23. 23.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  24. 24.√53 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  25. 25.Best estimate of 892 ÷ 68? (a) 130 (b) 1300 (c) 13
  26. 26.Best estimate of 1507 ÷ 72? (a) 2200 (b) 220 (c) 22
  27. 27.Best estimate of 1882 ÷ 52? (a) 38 (b) 3800 (c) 380
  28. 28.Best estimate of 7249 ÷ 78? (a) 91 (b) 9100 (c) 910
  29. 29.√79 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.2 (d) 9.0
  30. 30.Best estimate of 1731 ÷ 63? (a) 2900 (b) 290 (c) 29
  31. 31.√84 to 1 decimal place? (a) 9.2 (b) 9.5 (c) 9.3 (d) 9.4
  32. 32.Best estimate of 1220 ÷ 47? (a) 24 (b) 2400 (c) 240
  33. 33.√45 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  34. 34.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  35. 35.Best estimate of 1622 ÷ 84? (a) 2000 (b) 20 (c) 200
  36. 36.Best estimate of 2574 ÷ 76? (a) 32 (b) 3200 (c) 320
  37. 37.√98 to 1 decimal place? (a) 10.2 (b) 9.9 (c) 10.1 (d) 10.0
  38. 38.Best estimate of 435 ÷ 23? (a) 2200 (b) 22 (c) 220
  39. 39.Best estimate of 2658 ÷ 78? (a) 33 (b) 330 (c) 3300
  40. 40.Best estimate of 3623 ÷ 74? (a) 5200 (b) 520 (c) 52

Answer key

  1. 41
  2. 72
  3. 90
  4. 4.9
  5. 60
  6. 35
  7. 5.8
  8. 22
  9. 6.5
  10. 4.8
  11. 33
  12. 6.6
  13. 62
  14. 52
  15. 7.7
  16. 8.7
  17. 31
  18. 55
  19. 67
  20. 28
  21. 21
  22. 9.3
  23. 7.6
  24. 7.3
  25. 13
  26. 22
  27. 38
  28. 91
  29. 8.9
  30. 29
  31. 9.2
  32. 24
  33. 6.7
  34. 9.5
  35. 20
  36. 32
  37. 9.9
  38. 22
  39. 33
  40. 52

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