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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 602 · 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): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  2. 2.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?
  3. 3.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  5. 5.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  6. 6.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  7. 7.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  8. 8.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  9. 9.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  10. 10.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  12. 12.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  13. 13.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?
  14. 14.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  15. 15.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?
  16. 16.A leapfrog list starts 1, 4 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): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  18. 18.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  19. 19.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?
  20. 20.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  21. 21.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  22. 22.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?
  23. 23.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?
  24. 24.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  25. 25.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  26. 26.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?
  27. 27.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  28. 28.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?
  29. 29.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  30. 30.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  31. 31.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.Leapfrog list (each number is the sum of the two before it): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  33. 33.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  34. 34.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?
  35. 35.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.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?
  37. 37.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  40. 40.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =

Answer key

  1. 759
  2. 1034
  3. 1089
  4. 506
  5. 484
  6. 671
  7. 616
  8. 847
  9. 1023
  10. 429
  11. 858
  12. 605
  13. 869
  14. 759
  15. 946
  16. 407
  17. 704
  18. 1199
  19. 363
  20. 880
  21. 902
  22. 572
  23. 847
  24. 198
  25. 396
  26. 605
  27. 781
  28. 528
  29. 638
  30. 231
  31. 308
  32. 748
  33. 979
  34. 1232
  35. 924
  36. 869
  37. 253
  38. 759
  39. 627
  40. 913

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