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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 217 · 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 6743 ÷ 82? (a) 8400 (b) 84 (c) 840
  2. 2.√66 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  3. 3.√23 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.7 (d) 4.8
  4. 4.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.4
  5. 5.Best estimate of 1142 ÷ 64? (a) 190 (b) 1900 (c) 19
  6. 6.Best estimate of 1412 ÷ 64? (a) 2400 (b) 24 (c) 240
  7. 7.Best estimate of 7280 ÷ 81? (a) 910 (b) 9100 (c) 91
  8. 8.Best estimate of 1811 ÷ 23? (a) 9100 (b) 91 (c) 910
  9. 9.√86 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  10. 10.√21 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.6 (d) 4.8
  11. 11.Best estimate of 2709 ÷ 83? (a) 3400 (b) 34 (c) 340
  12. 12.√42 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.4
  13. 13.Best estimate of 3964 ÷ 54? (a) 7900 (b) 790 (c) 79
  14. 14.Best estimate of 2276 ÷ 32? (a) 760 (b) 76 (c) 7600
  15. 15.√52 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.4
  16. 16.Best estimate of 1990 ÷ 56? (a) 3300 (b) 33 (c) 330
  17. 17.Best estimate of 6083 ÷ 66? (a) 870 (b) 87 (c) 8700
  18. 18.Best estimate of 686 ÷ 36? (a) 170 (b) 17 (c) 1700
  19. 19.Best estimate of 1053 ÷ 21? (a) 530 (b) 53 (c) 5300
  20. 20.Best estimate of 4438 ÷ 52? (a) 89 (b) 8900 (c) 890
  21. 21.Best estimate of 3747 ÷ 56? (a) 62 (b) 6200 (c) 620
  22. 22.Best estimate of 2478 ÷ 38? (a) 6200 (b) 620 (c) 62
  23. 23.Best estimate of 2118 ÷ 49? (a) 420 (b) 4200 (c) 42
  24. 24.Best estimate of 1943 ÷ 54? (a) 39 (b) 390 (c) 3900
  25. 25.Best estimate of 410 ÷ 22? (a) 2100 (b) 210 (c) 21
  26. 26.√28 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.4 (d) 5.2
  27. 27.Best estimate of 1607 ÷ 68? (a) 230 (b) 23 (c) 2300
  28. 28.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  29. 29.Best estimate of 2735 ÷ 56? (a) 460 (b) 46 (c) 4600
  30. 30.Best estimate of 2526 ÷ 39? (a) 63 (b) 630 (c) 6300
  31. 31.Best estimate of 3477 ÷ 67? (a) 500 (b) 50 (c) 5000
  32. 32.√63 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 8.0
  33. 33.Best estimate of 1667 ÷ 36? (a) 42 (b) 420 (c) 4200
  34. 34.Best estimate of 1183 ÷ 73? (a) 1700 (b) 170 (c) 17
  35. 35.Best estimate of 2458 ÷ 72? (a) 3500 (b) 350 (c) 35
  36. 36.√51 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.1
  37. 37.Best estimate of 1254 ÷ 77? (a) 160 (b) 16 (c) 1600
  38. 38.Best estimate of 2592 ÷ 61? (a) 4300 (b) 43 (c) 430
  39. 39.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.3 (d) 8.4
  40. 40.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.7 (d) 7.6

Answer key

  1. 84
  2. 8.1
  3. 4.8
  4. 7.6
  5. 19
  6. 24
  7. 91
  8. 91
  9. 9.3
  10. 4.6
  11. 34
  12. 6.5
  13. 79
  14. 76
  15. 7.2
  16. 33
  17. 87
  18. 17
  19. 53
  20. 89
  21. 62
  22. 62
  23. 42
  24. 39
  25. 21
  26. 5.3
  27. 23
  28. 9.4
  29. 46
  30. 63
  31. 50
  32. 7.9
  33. 42
  34. 17
  35. 35
  36. 7.1
  37. 16
  38. 43
  39. 8.6
  40. 7.4

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