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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 623 · 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.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.0
  2. 2.√22 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.4 (d) 4.6
  3. 3.Best estimate of 986 ÷ 67? (a) 140 (b) 14 (c) 1400
  4. 4.Best estimate of 2927 ÷ 39? (a) 7300 (b) 730 (c) 73
  5. 5.Best estimate of 1936 ÷ 56? (a) 3200 (b) 320 (c) 32
  6. 6.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  7. 7.Best estimate of 3416 ÷ 71? (a) 4900 (b) 490 (c) 49
  8. 8.√21 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.4 (d) 4.3
  9. 9.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 6.6
  10. 10.Best estimate of 1455 ÷ 28? (a) 490 (b) 49 (c) 4900
  11. 11.Best estimate of 1997 ÷ 73? (a) 290 (b) 29 (c) 2900
  12. 12.Best estimate of 1112 ÷ 39? (a) 280 (b) 2800 (c) 28
  13. 13.Best estimate of 2248 ÷ 57? (a) 37 (b) 370 (c) 3700
  14. 14.√53 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.2
  15. 15.Best estimate of 1752 ÷ 62? (a) 29 (b) 290 (c) 2900
  16. 16.Best estimate of 2985 ÷ 39? (a) 750 (b) 75 (c) 7500
  17. 17.Best estimate of 940 ÷ 47? (a) 190 (b) 19 (c) 1900
  18. 18.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.8
  19. 19.Best estimate of 1034 ÷ 79? (a) 13 (b) 1300 (c) 130
  20. 20.Best estimate of 1105 ÷ 51? (a) 2200 (b) 220 (c) 22
  21. 21.√87 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.0
  22. 22.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  23. 23.Best estimate of 3441 ÷ 58? (a) 5700 (b) 570 (c) 57
  24. 24.Best estimate of 1158 ÷ 27? (a) 390 (b) 39 (c) 3900
  25. 25.Best estimate of 1553 ÷ 52? (a) 31 (b) 310 (c) 3100
  26. 26.√70 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  27. 27.Best estimate of 2669 ÷ 89? (a) 30 (b) 300 (c) 3000
  28. 28.√40 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  29. 29.Best estimate of 1109 ÷ 26? (a) 3700 (b) 37 (c) 370
  30. 30.√51 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.9 (d) 7.1
  31. 31.Best estimate of 2265 ÷ 76? (a) 28 (b) 280 (c) 2800
  32. 32.Best estimate of 2382 ÷ 37? (a) 60 (b) 600 (c) 6000
  33. 33.√41 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  34. 34.√65 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  35. 35.Best estimate of 4968 ÷ 78? (a) 62 (b) 6200 (c) 620
  36. 36.√94 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.7
  37. 37.Best estimate of 993 ÷ 32? (a) 33 (b) 3300 (c) 330
  38. 38.Best estimate of 7688 ÷ 82? (a) 9600 (b) 960 (c) 96
  39. 39.Best estimate of 879 ÷ 41? (a) 220 (b) 2200 (c) 22
  40. 40.√52 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.1 (d) 7.2

Answer key

  1. 9.1
  2. 4.7
  3. 14
  4. 73
  5. 32
  6. 9.9
  7. 49
  8. 4.6
  9. 6.7
  10. 49
  11. 29
  12. 28
  13. 37
  14. 7.3
  15. 29
  16. 75
  17. 19
  18. 7.6
  19. 13
  20. 22
  21. 9.3
  22. 7.4
  23. 57
  24. 39
  25. 31
  26. 8.4
  27. 30
  28. 6.3
  29. 37
  30. 7.1
  31. 28
  32. 60
  33. 6.4
  34. 8.1
  35. 62
  36. 9.7
  37. 33
  38. 96
  39. 22
  40. 7.2

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