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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 619 · 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 5932 ÷ 62? (a) 990 (b) 99 (c) 9900
  2. 2.Best estimate of 3396 ÷ 64? (a) 57 (b) 5700 (c) 570
  3. 3.√88 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  4. 4.Best estimate of 2081 ÷ 23? (a) 1040 (b) 10400 (c) 104
  5. 5.Best estimate of 3579 ÷ 88? (a) 40 (b) 400 (c) 4000
  6. 6.Best estimate of 1330 ÷ 36? (a) 330 (b) 3300 (c) 33
  7. 7.√96 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.8 (d) 9.9
  8. 8.√41 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.6
  9. 9.Best estimate of 3477 ÷ 47? (a) 70 (b) 7000 (c) 700
  10. 10.√37 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 5.8 (d) 6.0
  11. 11.Best estimate of 1355 ÷ 43? (a) 340 (b) 3400 (c) 34
  12. 12.√80 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  13. 13.√62 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 7.8 (d) 8.0
  14. 14.√26 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.2 (d) 5.1
  15. 15.Best estimate of 2613 ÷ 81? (a) 33 (b) 330 (c) 3300
  16. 16.Best estimate of 821 ÷ 46? (a) 160 (b) 16 (c) 1600
  17. 17.Best estimate of 1053 ÷ 66? (a) 15 (b) 150 (c) 1500
  18. 18.√21 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.6 (d) 4.7
  19. 19.Best estimate of 2049 ÷ 37? (a) 51 (b) 510 (c) 5100
  20. 20.√50 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  21. 21.Best estimate of 4639 ÷ 56? (a) 770 (b) 7700 (c) 77
  22. 22.Best estimate of 2857 ÷ 88? (a) 32 (b) 320 (c) 3200
  23. 23.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  24. 24.Best estimate of 3285 ÷ 56? (a) 5500 (b) 550 (c) 55
  25. 25.Best estimate of 688 ÷ 32? (a) 23 (b) 230 (c) 2300
  26. 26.Best estimate of 2511 ÷ 68? (a) 360 (b) 3600 (c) 36
  27. 27.√55 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.4 (d) 7.2
  28. 28.√44 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.8 (d) 6.6
  29. 29.√48 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.7 (d) 6.9
  30. 30.Best estimate of 1836 ÷ 68? (a) 26 (b) 2600 (c) 260
  31. 31.√59 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.5 (d) 7.7
  32. 32.Best estimate of 2082 ÷ 23? (a) 10400 (b) 104 (c) 1040
  33. 33.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  34. 34.Best estimate of 1438 ÷ 23? (a) 7200 (b) 720 (c) 72
  35. 35.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  36. 36.Best estimate of 7504 ÷ 79? (a) 94 (b) 9400 (c) 940
  37. 37.√71 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.3
  38. 38.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.0
  39. 39.√85 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.5 (d) 9.4
  40. 40.Best estimate of 6739 ÷ 83? (a) 8400 (b) 84 (c) 840

Answer key

  1. 99
  2. 57
  3. 9.4
  4. 104
  5. 40
  6. 33
  7. 9.8
  8. 6.4
  9. 70
  10. 6.1
  11. 34
  12. 8.9
  13. 7.9
  14. 5.1
  15. 33
  16. 16
  17. 15
  18. 4.6
  19. 51
  20. 7.1
  21. 77
  22. 32
  23. 6.2
  24. 55
  25. 23
  26. 36
  27. 7.4
  28. 6.6
  29. 6.9
  30. 26
  31. 7.7
  32. 104
  33. 7.6
  34. 72
  35. 8.6
  36. 94
  37. 8.4
  38. 6.3
  39. 9.2
  40. 84

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