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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 960 · 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): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  3. 3.A leapfrog list starts 3, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  6. 6.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?
  7. 7.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?
  8. 8.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  9. 9.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?
  10. 10.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  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.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?
  13. 13.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?
  14. 14.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?
  15. 15.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  16. 16.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  17. 17.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  18. 18.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  19. 19.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  20. 20.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?
  21. 21.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  23. 23.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  24. 24.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  27. 27.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  28. 28.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  29. 29.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  31. 31.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  33. 33.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?
  34. 34.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  35. 35.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?
  36. 36.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.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?
  38. 38.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 935
  2. 715
  3. 781
  4. 759
  5. 1232
  6. 946
  7. 561
  8. 913
  9. 759
  10. 583
  11. 858
  12. 231
  13. 495
  14. 341
  15. 891
  16. 957
  17. 737
  18. 451
  19. 308
  20. 671
  21. 682
  22. 418
  23. 979
  24. 671
  25. 1287
  26. 792
  27. 539
  28. 143
  29. 693
  30. 1122
  31. 726
  32. 528
  33. 1067
  34. 561
  35. 704
  36. 913
  37. 847
  38. 319
  39. 913
  40. 550

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