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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 978 · 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.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?
  3. 3.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  5. 5.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  6. 6.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?
  7. 7.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  8. 8.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  9. 9.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  10. 10.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  11. 11.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  12. 12.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  13. 13.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  14. 14.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  15. 15.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  17. 17.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  18. 18.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  19. 19.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?
  20. 20.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?
  21. 21.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?
  22. 22.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  23. 23.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  24. 24.A leapfrog list starts 3, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  26. 26.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  28. 28.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  30. 30.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  31. 31.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  32. 32.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?
  33. 33.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  34. 34.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  37. 37.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  38. 38.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  40. 40.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?

Answer key

  1. 506
  2. 308
  3. 495
  4. 418
  5. 363
  6. 946
  7. 550
  8. 649
  9. 561
  10. 1111
  11. 847
  12. 616
  13. 825
  14. 583
  15. 1177
  16. 429
  17. 715
  18. 341
  19. 429
  20. 847
  21. 847
  22. 319
  23. 770
  24. 869
  25. 924
  26. 759
  27. 308
  28. 891
  29. 429
  30. 583
  31. 671
  32. 517
  33. 869
  34. 671
  35. 770
  36. 814
  37. 418
  38. 484
  39. 968
  40. 770

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