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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 204 · 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.√88 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  2. 2.Best estimate of 848 ÷ 27? (a) 280 (b) 28 (c) 2800
  3. 3.Best estimate of 912 ÷ 26? (a) 300 (b) 30 (c) 3000
  4. 4.Best estimate of 1433 ÷ 26? (a) 480 (b) 48 (c) 4800
  5. 5.Best estimate of 2272 ÷ 72? (a) 320 (b) 3200 (c) 32
  6. 6.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 5.8 (d) 6.0
  7. 7.Best estimate of 636 ÷ 34? (a) 2100 (b) 210 (c) 21
  8. 8.Best estimate of 770 ÷ 64? (a) 1300 (b) 13 (c) 130
  9. 9.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  10. 10.Best estimate of 1555 ÷ 42? (a) 39 (b) 3900 (c) 390
  11. 11.Best estimate of 1608 ÷ 69? (a) 23 (b) 230 (c) 2300
  12. 12.√76 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.9
  13. 13.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.4
  14. 14.Best estimate of 3040 ÷ 41? (a) 760 (b) 76 (c) 7600
  15. 15.Best estimate of 7120 ÷ 78? (a) 89 (b) 890 (c) 8900
  16. 16.Best estimate of 2763 ÷ 57? (a) 4600 (b) 460 (c) 46
  17. 17.Best estimate of 4420 ÷ 77? (a) 55 (b) 5500 (c) 550
  18. 18.√71 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.2 (d) 8.4
  19. 19.√32 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 5.7
  20. 20.√20 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.3 (d) 4.5
  21. 21.√89 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  22. 22.Best estimate of 2140 ÷ 24? (a) 10700 (b) 1070 (c) 107
  23. 23.Best estimate of 2748 ÷ 46? (a) 5500 (b) 55 (c) 550
  24. 24.Best estimate of 5489 ÷ 74? (a) 780 (b) 7800 (c) 78
  25. 25.Best estimate of 4033 ÷ 73? (a) 5800 (b) 58 (c) 580
  26. 26.Best estimate of 5299 ÷ 87? (a) 590 (b) 59 (c) 5900
  27. 27.Best estimate of 1598 ÷ 37? (a) 40 (b) 4000 (c) 400
  28. 28.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  29. 29.√31 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.9 (d) 5.6
  30. 30.√45 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.7 (d) 6.6
  31. 31.Best estimate of 788 ÷ 46? (a) 160 (b) 16 (c) 1600
  32. 32.Best estimate of 1516 ÷ 72? (a) 2200 (b) 220 (c) 22
  33. 33.Best estimate of 1134 ÷ 39? (a) 280 (b) 2800 (c) 28
  34. 34.Best estimate of 607 ÷ 37? (a) 1500 (b) 150 (c) 15
  35. 35.√69 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  36. 36.Best estimate of 1056 ÷ 44? (a) 26 (b) 2600 (c) 260
  37. 37.Best estimate of 1177 ÷ 38? (a) 290 (b) 2900 (c) 29
  38. 38.√53 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  39. 39.√30 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.2 (d) 5.3
  40. 40.Best estimate of 1752 ÷ 73? (a) 250 (b) 2500 (c) 25

Answer key

  1. 9.4
  2. 28
  3. 30
  4. 48
  5. 32
  6. 6.1
  7. 21
  8. 13
  9. 9.5
  10. 39
  11. 23
  12. 8.7
  13. 9.1
  14. 76
  15. 89
  16. 46
  17. 55
  18. 8.4
  19. 5.7
  20. 4.5
  21. 9.4
  22. 107
  23. 55
  24. 78
  25. 58
  26. 59
  27. 40
  28. 9.9
  29. 5.6
  30. 6.7
  31. 16
  32. 22
  33. 28
  34. 15
  35. 8.3
  36. 26
  37. 29
  38. 7.3
  39. 5.5
  40. 25

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