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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 563 · 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 3053 ÷ 49? (a) 6100 (b) 61 (c) 610
  2. 2.Best estimate of 2089 ÷ 24? (a) 1040 (b) 10400 (c) 104
  3. 3.Best estimate of 1078 ÷ 56? (a) 180 (b) 18 (c) 1800
  4. 4.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.6 (d) 6.5
  5. 5.Best estimate of 5428 ÷ 83? (a) 6800 (b) 68 (c) 680
  6. 6.Best estimate of 2441 ÷ 82? (a) 3100 (b) 310 (c) 31
  7. 7.Best estimate of 4525 ÷ 62? (a) 750 (b) 75 (c) 7500
  8. 8.√90 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.5 (d) 9.7
  9. 9.Best estimate of 4546 ÷ 87? (a) 510 (b) 5100 (c) 51
  10. 10.√58 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.4 (d) 7.5
  11. 11.√27 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.1
  12. 12.Best estimate of 1248 ÷ 52? (a) 2500 (b) 250 (c) 25
  13. 13.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 10.1
  14. 14.Best estimate of 2213 ÷ 43? (a) 550 (b) 55 (c) 5500
  15. 15.√78 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 8.7
  16. 16.Best estimate of 3449 ÷ 43? (a) 86 (b) 8600 (c) 860
  17. 17.√72 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.3 (d) 8.6
  18. 18.Best estimate of 6030 ÷ 66? (a) 860 (b) 8600 (c) 86
  19. 19.Best estimate of 867 ÷ 29? (a) 290 (b) 2900 (c) 29
  20. 20.Best estimate of 3371 ÷ 42? (a) 84 (b) 8400 (c) 840
  21. 21.√32 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.7 (d) 5.5
  22. 22.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.7
  23. 23.Best estimate of 703 ÷ 26? (a) 230 (b) 23 (c) 2300
  24. 24.√20 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.8 (d) 4.6
  25. 25.Best estimate of 1486 ÷ 46? (a) 30 (b) 3000 (c) 300
  26. 26.Best estimate of 620 ÷ 29? (a) 21 (b) 2100 (c) 210
  27. 27.√41 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  28. 28.Best estimate of 3379 ÷ 66? (a) 4800 (b) 480 (c) 48
  29. 29.Best estimate of 586 ÷ 23? (a) 2900 (b) 290 (c) 29
  30. 30.Best estimate of 3626 ÷ 86? (a) 4000 (b) 400 (c) 40
  31. 31.Best estimate of 1546 ÷ 33? (a) 5200 (b) 52 (c) 520
  32. 32.√79 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  33. 33.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.4 (d) 8.3
  34. 34.Best estimate of 676 ÷ 32? (a) 230 (b) 2300 (c) 23
  35. 35.Best estimate of 2489 ÷ 44? (a) 6200 (b) 620 (c) 62
  36. 36.√48 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.7 (d) 6.8
  37. 37.Best estimate of 5159 ÷ 66? (a) 7400 (b) 740 (c) 74
  38. 38.Best estimate of 957 ÷ 56? (a) 16 (b) 1600 (c) 160
  39. 39.Best estimate of 1516 ÷ 23? (a) 76 (b) 760 (c) 7600
  40. 40.Best estimate of 1620 ÷ 79? (a) 2000 (b) 200 (c) 20

Answer key

  1. 61
  2. 104
  3. 18
  4. 6.3
  5. 68
  6. 31
  7. 75
  8. 9.5
  9. 51
  10. 7.6
  11. 5.2
  12. 25
  13. 9.9
  14. 55
  15. 8.8
  16. 86
  17. 8.5
  18. 86
  19. 29
  20. 84
  21. 5.7
  22. 7.4
  23. 23
  24. 4.5
  25. 30
  26. 21
  27. 6.4
  28. 48
  29. 29
  30. 40
  31. 52
  32. 8.9
  33. 8.3
  34. 23
  35. 62
  36. 6.9
  37. 74
  38. 16
  39. 76
  40. 20

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