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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 867 · 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 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  4. 4.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  5. 5.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  6. 6.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  7. 7.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  8. 8.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  9. 9.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  10. 10.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  12. 12.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?
  13. 13.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  14. 14.A leapfrog list starts 9, 5 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): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  16. 16.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?
  17. 17.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?
  18. 18.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  19. 19.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  20. 20.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  21. 21.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  23. 23.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?
  24. 24.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  25. 25.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  26. 26.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  28. 28.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?
  29. 29.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  31. 31.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  32. 32.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  34. 34.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  36. 36.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?
  37. 37.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  38. 38.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 902
  2. 286
  3. 308
  4. 1111
  5. 583
  6. 847
  7. 616
  8. 517
  9. 770
  10. 198
  11. 1067
  12. 429
  13. 539
  14. 935
  15. 616
  16. 319
  17. 495
  18. 286
  19. 1199
  20. 814
  21. 968
  22. 880
  23. 847
  24. 792
  25. 374
  26. 583
  27. 759
  28. 517
  29. 341
  30. 946
  31. 418
  32. 1023
  33. 759
  34. 1144
  35. 726
  36. 638
  37. 924
  38. 979
  39. 539
  40. 847

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