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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 349 · 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.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.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?
  4. 4.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  5. 5.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  6. 6.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  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.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?
  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. 10.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  11. 11.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?
  12. 12.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  13. 13.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?
  14. 14.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  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 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  18. 18.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?
  19. 19.A leapfrog list starts 4, 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): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  21. 21.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  22. 22.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?
  23. 23.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  24. 24.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  25. 25.A leapfrog list starts 8, 9 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): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  27. 27.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  29. 29.A leapfrog list starts 5, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.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?
  31. 31.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?
  32. 32.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  33. 33.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  34. 34.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  36. 36.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?
  37. 37.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  38. 38.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?

Answer key

  1. 1199
  2. 693
  3. 605
  4. 143
  5. 374
  6. 319
  7. 550
  8. 957
  9. 946
  10. 374
  11. 638
  12. 792
  13. 847
  14. 561
  15. 1287
  16. 231
  17. 1089
  18. 704
  19. 484
  20. 891
  21. 814
  22. 869
  23. 517
  24. 473
  25. 1232
  26. 957
  27. 506
  28. 583
  29. 1067
  30. 616
  31. 539
  32. 913
  33. 979
  34. 561
  35. 902
  36. 1287
  37. 880
  38. 528
  39. 198
  40. 396

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