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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 525 · 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.√43 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.6
  2. 2.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.9 (d) 9.8
  3. 3.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  4. 4.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  5. 5.√58 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.6
  6. 6.√71 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.6
  7. 7.Best estimate of 1475 ÷ 42? (a) 370 (b) 37 (c) 3700
  8. 8.Best estimate of 5747 ÷ 62? (a) 960 (b) 96 (c) 9600
  9. 9.√35 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.6 (d) 5.8
  10. 10.Best estimate of 668 ÷ 42? (a) 170 (b) 1700 (c) 17
  11. 11.Best estimate of 2312 ÷ 76? (a) 2900 (b) 290 (c) 29
  12. 12.Best estimate of 3173 ÷ 56? (a) 5300 (b) 53 (c) 530
  13. 13.Best estimate of 3538 ÷ 38? (a) 88 (b) 880 (c) 8800
  14. 14.√59 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  15. 15.Best estimate of 2152 ÷ 51? (a) 43 (b) 430 (c) 4300
  16. 16.Best estimate of 4014 ÷ 74? (a) 57 (b) 5700 (c) 570
  17. 17.Best estimate of 1547 ÷ 56? (a) 260 (b) 26 (c) 2600
  18. 18.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.8 (d) 7.9
  19. 19.Best estimate of 1372 ÷ 36? (a) 3400 (b) 34 (c) 340
  20. 20.Best estimate of 1653 ÷ 86? (a) 180 (b) 1800 (c) 18
  21. 21.Best estimate of 706 ÷ 39? (a) 180 (b) 1800 (c) 18
  22. 22.Best estimate of 1180 ÷ 36? (a) 3000 (b) 30 (c) 300
  23. 23.Best estimate of 974 ÷ 34? (a) 32 (b) 320 (c) 3200
  24. 24.Best estimate of 1198 ÷ 46? (a) 2400 (b) 240 (c) 24
  25. 25.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  26. 26.Best estimate of 5495 ÷ 66? (a) 7900 (b) 790 (c) 79
  27. 27.√87 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.6 (d) 9.5
  28. 28.Best estimate of 2537 ÷ 48? (a) 5100 (b) 51 (c) 510
  29. 29.√69 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.3
  30. 30.Best estimate of 2305 ÷ 81? (a) 2900 (b) 290 (c) 29
  31. 31.√26 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 4.9 (d) 5.0
  32. 32.Best estimate of 479 ÷ 29? (a) 1600 (b) 16 (c) 160
  33. 33.√48 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.6 (d) 6.7
  34. 34.Best estimate of 4370 ÷ 52? (a) 870 (b) 8700 (c) 87
  35. 35.Best estimate of 2332 ÷ 69? (a) 33 (b) 330 (c) 3300
  36. 36.Best estimate of 658 ÷ 52? (a) 130 (b) 13 (c) 1300
  37. 37.Best estimate of 1721 ÷ 52? (a) 340 (b) 3400 (c) 34
  38. 38.Best estimate of 966 ÷ 32? (a) 32 (b) 320 (c) 3200
  39. 39.Best estimate of 2625 ÷ 51? (a) 5300 (b) 53 (c) 530
  40. 40.Best estimate of 4139 ÷ 67? (a) 5900 (b) 590 (c) 59

Answer key

  1. 6.6
  2. 9.7
  3. 6.2
  4. 6.3
  5. 7.6
  6. 8.4
  7. 37
  8. 96
  9. 5.9
  10. 17
  11. 29
  12. 53
  13. 88
  14. 7.7
  15. 43
  16. 57
  17. 26
  18. 8.1
  19. 34
  20. 18
  21. 18
  22. 30
  23. 32
  24. 24
  25. 9.6
  26. 79
  27. 9.3
  28. 51
  29. 8.3
  30. 29
  31. 5.1
  32. 16
  33. 6.9
  34. 87
  35. 33
  36. 13
  37. 34
  38. 32
  39. 53
  40. 59

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