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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 669 · 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 3728 ÷ 64? (a) 62 (b) 620 (c) 6200
  2. 2.Best estimate of 2729 ÷ 77? (a) 340 (b) 3400 (c) 34
  3. 3.Best estimate of 758 ÷ 44? (a) 19 (b) 1900 (c) 190
  4. 4.Best estimate of 1624 ÷ 39? (a) 41 (b) 4100 (c) 410
  5. 5.Best estimate of 3885 ÷ 47? (a) 780 (b) 7800 (c) 78
  6. 6.Best estimate of 5858 ÷ 74? (a) 840 (b) 84 (c) 8400
  7. 7.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  8. 8.√47 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.0 (d) 7.2
  9. 9.Best estimate of 6091 ÷ 79? (a) 760 (b) 7600 (c) 76
  10. 10.Best estimate of 8076 ÷ 86? (a) 9000 (b) 90 (c) 900
  11. 11.√98 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  12. 12.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.2 (d) 4.9
  13. 13.√32 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.6 (d) 5.7
  14. 14.√58 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.5
  15. 15.√69 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.4 (d) 8.5
  16. 16.√41 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  17. 17.Best estimate of 1763 ÷ 78? (a) 22 (b) 220 (c) 2200
  18. 18.Best estimate of 5164 ÷ 66? (a) 74 (b) 740 (c) 7400
  19. 19.Best estimate of 1834 ÷ 72? (a) 260 (b) 26 (c) 2600
  20. 20.Best estimate of 1002 ÷ 73? (a) 140 (b) 14 (c) 1400
  21. 21.Best estimate of 509 ÷ 42? (a) 130 (b) 1300 (c) 13
  22. 22.√34 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  23. 23.√59 to 1 decimal place? (a) 7.4 (b) 7.7 (c) 7.6 (d) 7.5
  24. 24.Best estimate of 1262 ÷ 24? (a) 6300 (b) 630 (c) 63
  25. 25.√37 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  26. 26.Best estimate of 5048 ÷ 84? (a) 63 (b) 6300 (c) 630
  27. 27.Best estimate of 7796 ÷ 86? (a) 870 (b) 8700 (c) 87
  28. 28.Best estimate of 1767 ÷ 68? (a) 250 (b) 25 (c) 2500
  29. 29.Best estimate of 487 ÷ 28? (a) 1600 (b) 160 (c) 16
  30. 30.Best estimate of 1916 ÷ 43? (a) 4800 (b) 480 (c) 48
  31. 31.Best estimate of 1279 ÷ 54? (a) 26 (b) 260 (c) 2600
  32. 32.Best estimate of 645 ÷ 33? (a) 220 (b) 22 (c) 2200
  33. 33.Best estimate of 977 ÷ 34? (a) 3300 (b) 330 (c) 33
  34. 34.Best estimate of 1975 ÷ 89? (a) 2200 (b) 22 (c) 220
  35. 35.Best estimate of 2029 ÷ 38? (a) 51 (b) 5100 (c) 510
  36. 36.Best estimate of 4674 ÷ 57? (a) 7800 (b) 78 (c) 780
  37. 37.Best estimate of 4947 ÷ 73? (a) 7100 (b) 71 (c) 710
  38. 38.Best estimate of 2515 ÷ 62? (a) 420 (b) 4200 (c) 42
  39. 39.Best estimate of 2425 ÷ 32? (a) 8100 (b) 81 (c) 810
  40. 40.√35 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 5.9

Answer key

  1. 62
  2. 34
  3. 19
  4. 41
  5. 78
  6. 84
  7. 8.1
  8. 6.9
  9. 76
  10. 90
  11. 9.9
  12. 5.1
  13. 5.7
  14. 7.6
  15. 8.3
  16. 6.4
  17. 22
  18. 74
  19. 26
  20. 14
  21. 13
  22. 5.8
  23. 7.7
  24. 63
  25. 6.1
  26. 63
  27. 87
  28. 25
  29. 16
  30. 48
  31. 26
  32. 22
  33. 33
  34. 22
  35. 51
  36. 78
  37. 71
  38. 42
  39. 81
  40. 5.9

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