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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 990 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  2. 2.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  3. 3.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
  5. 5.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  6. 6.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  7. 7.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  8. 8.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  9. 9.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  10. 10.A leapfrog list starts 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  14. 14.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  16. 16.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.A leapfrog list starts 1, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  21. 21.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  22. 22.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  23. 23.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  25. 25.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  26. 26.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  29. 29.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  30. 30.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  32. 32.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  33. 33.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  34. 34.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  36. 36.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  37. 37.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  40. 40.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?

Answer key

  1. 506
  2. 1287
  3. 825
  4. 770
  5. 935
  6. 759
  7. 451
  8. 946
  9. 462
  10. 858
  11. 847
  12. 572
  13. 484
  14. 924
  15. 583
  16. 968
  17. 638
  18. 143
  19. 539
  20. 396
  21. 803
  22. 319
  23. 693
  24. 1034
  25. 1232
  26. 803
  27. 539
  28. 627
  29. 407
  30. 561
  31. 792
  32. 286
  33. 693
  34. 286
  35. 1177
  36. 605
  37. 198
  38. 704
  39. 847
  40. 143

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