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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 84 · 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, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  2. 2.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  3. 3.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  4. 4.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  5. 5.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  6. 6.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  7. 7.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?
  8. 8.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?
  9. 9.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  10. 10.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?
  11. 11.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  12. 12.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  13. 13.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?
  14. 14.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?
  15. 15.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?
  16. 16.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?
  17. 17.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  18. 18.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?
  19. 19.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  20. 20.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  21. 21.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  22. 22.A leapfrog list starts 5, 1 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): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  24. 24.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?
  25. 25.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  26. 26.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?
  27. 27.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  28. 28.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  29. 29.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?
  30. 30.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  31. 31.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  32. 32.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  33. 33.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  34. 34.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?
  35. 35.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  37. 37.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?
  38. 38.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  40. 40.A leapfrog list starts 7, 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. 726
  2. 759
  3. 506
  4. 572
  5. 363
  6. 946
  7. 1056
  8. 1287
  9. 1144
  10. 616
  11. 704
  12. 847
  13. 495
  14. 935
  15. 396
  16. 957
  17. 374
  18. 517
  19. 869
  20. 198
  21. 517
  22. 363
  23. 737
  24. 605
  25. 1111
  26. 396
  27. 1089
  28. 913
  29. 528
  30. 462
  31. 935
  32. 649
  33. 979
  34. 627
  35. 594
  36. 484
  37. 506
  38. 1287
  39. 649
  40. 825

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