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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 275 · 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): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  2. 2.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  3. 3.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  4. 4.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  5. 5.A leapfrog list starts 4, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.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?
  7. 7.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?
  8. 8.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  10. 10.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?
  11. 11.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?
  12. 12.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  13. 13.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  14. 14.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?
  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.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?
  17. 17.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  18. 18.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?
  19. 19.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?
  20. 20.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  21. 21.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?
  22. 22.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  23. 23.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  25. 25.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  26. 26.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?
  27. 27.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  28. 28.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  29. 29.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  30. 30.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?
  31. 31.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  32. 32.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  33. 33.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  35. 35.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?
  36. 36.A leapfrog list starts 2, 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 5, 5 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 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  40. 40.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?

Answer key

  1. 550
  2. 286
  3. 253
  4. 341
  5. 1012
  6. 550
  7. 759
  8. 847
  9. 781
  10. 451
  11. 660
  12. 902
  13. 605
  14. 1034
  15. 1287
  16. 638
  17. 1111
  18. 319
  19. 748
  20. 715
  21. 517
  22. 429
  23. 143
  24. 836
  25. 847
  26. 583
  27. 869
  28. 693
  29. 880
  30. 1177
  31. 814
  32. 396
  33. 726
  34. 1056
  35. 704
  36. 462
  37. 715
  38. 396
  39. 671
  40. 495

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