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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 756 · 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): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  2. 2.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  3. 3.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  4. 4.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?
  5. 5.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  6. 6.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  7. 7.A leapfrog list starts 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  9. 9.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?
  10. 10.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  11. 11.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  12. 12.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?
  13. 13.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  14. 14.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  15. 15.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?
  16. 16.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  18. 18.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  19. 19.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  20. 20.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  21. 21.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  22. 22.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?
  23. 23.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  25. 25.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?
  26. 26.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?
  27. 27.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?
  28. 28.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  29. 29.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?
  30. 30.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  31. 31.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  33. 33.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?
  34. 34.A leapfrog list starts 9, 1 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 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  37. 37.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  38. 38.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  39. 39.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?

Answer key

  1. 968
  2. 418
  3. 1067
  4. 341
  5. 473
  6. 429
  7. 495
  8. 1287
  9. 946
  10. 748
  11. 583
  12. 957
  13. 605
  14. 704
  15. 770
  16. 1177
  17. 638
  18. 286
  19. 286
  20. 781
  21. 891
  22. 770
  23. 847
  24. 1144
  25. 429
  26. 1122
  27. 935
  28. 946
  29. 616
  30. 1056
  31. 528
  32. 759
  33. 561
  34. 583
  35. 396
  36. 803
  37. 660
  38. 737
  39. 693
  40. 682

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