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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 830 · 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. 1.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  2. 2.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  3. 3.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.A leapfrog list starts 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.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?
  6. 6.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  7. 7.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  8. 8.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?
  9. 9.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  10. 10.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  11. 11.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  12. 12.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?
  13. 13.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  14. 14.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  15. 15.A leapfrog list starts 9, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  17. 17.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  18. 18.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  19. 19.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  20. 20.A leapfrog list starts 2, 3 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): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  22. 22.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?
  23. 23.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  24. 24.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  25. 25.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  27. 27.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  28. 28.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  30. 30.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  31. 31.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  33. 33.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?
  34. 34.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  37. 37.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  38. 38.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  39. 39.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =

Answer key

  1. 583
  2. 451
  3. 627
  4. 605
  5. 429
  6. 451
  7. 1122
  8. 825
  9. 847
  10. 1177
  11. 429
  12. 539
  13. 759
  14. 1067
  15. 1287
  16. 979
  17. 198
  18. 1034
  19. 649
  20. 374
  21. 803
  22. 1177
  23. 1001
  24. 770
  25. 814
  26. 319
  27. 396
  28. 550
  29. 792
  30. 286
  31. 979
  32. 1023
  33. 319
  34. 748
  35. 198
  36. 572
  37. 1012
  38. 836
  39. 715
  40. 495

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