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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 575 · 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, 7 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 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  4. 4.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  6. 6.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  8. 8.A leapfrog list starts 6, 7 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): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  11. 11.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?
  12. 12.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?
  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.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.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?
  16. 16.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?
  17. 17.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?
  18. 18.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  19. 19.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?
  20. 20.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  21. 21.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  22. 22.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  23. 23.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?
  24. 24.A leapfrog list starts 8, 7 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): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  26. 26.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?
  27. 27.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?
  28. 28.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?
  29. 29.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  30. 30.A leapfrog list starts 2, 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 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  32. 32.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  33. 33.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?
  34. 34.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  35. 35.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  36. 36.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?
  37. 37.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  38. 38.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  39. 39.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  40. 40.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =

Answer key

  1. 1111
  2. 418
  3. 308
  4. 561
  5. 902
  6. 814
  7. 396
  8. 946
  9. 913
  10. 671
  11. 946
  12. 198
  13. 605
  14. 1034
  15. 935
  16. 495
  17. 869
  18. 495
  19. 891
  20. 539
  21. 231
  22. 671
  23. 429
  24. 1056
  25. 319
  26. 506
  27. 737
  28. 572
  29. 429
  30. 902
  31. 198
  32. 1089
  33. 1287
  34. 649
  35. 935
  36. 1012
  37. 473
  38. 231
  39. 671
  40. 902

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