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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 101 · 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. 1.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  2. 2.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  4. 4.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  5. 5.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  7. 7.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  8. 8.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  11. 11.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  12. 12.Leapfrog list (each number is the sum of the two before it): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  13. 13.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  15. 15.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  16. 16.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  17. 17.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  18. 18.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  19. 19.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.Leapfrog list (each number is the sum of the two before it): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  21. 21.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?
  22. 22.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  23. 23.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  25. 25.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  26. 26.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  27. 27.A leapfrog list starts 4, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  29. 29.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  30. 30.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  33. 33.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  34. 34.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  35. 35.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  36. 36.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?
  37. 37.A leapfrog list starts 3, 3 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 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  40. 40.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 605
  2. 616
  3. 869
  4. 1122
  5. 308
  6. 781
  7. 539
  8. 1177
  9. 341
  10. 902
  11. 946
  12. 517
  13. 1034
  14. 1122
  15. 561
  16. 374
  17. 770
  18. 484
  19. 594
  20. 616
  21. 583
  22. 715
  23. 253
  24. 847
  25. 649
  26. 759
  27. 660
  28. 847
  29. 968
  30. 957
  31. 1122
  32. 1177
  33. 847
  34. 814
  35. 660
  36. 572
  37. 429
  38. 231
  39. 253
  40. 319

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