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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 770 · 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): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  3. 3.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  6. 6.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  7. 7.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  9. 9.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  10. 10.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?
  11. 11.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  12. 12.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  13. 13.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?
  14. 14.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?
  15. 15.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  16. 16.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  17. 17.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  20. 20.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?
  21. 21.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  22. 22.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  23. 23.A leapfrog list starts 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  26. 26.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  27. 27.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?
  28. 28.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?
  29. 29.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?
  30. 30.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  31. 31.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  35. 35.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  36. 36.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  37. 37.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?
  38. 38.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?
  39. 39.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  40. 40.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?

Answer key

  1. 418
  2. 363
  3. 715
  4. 1067
  5. 473
  6. 891
  7. 451
  8. 583
  9. 319
  10. 671
  11. 671
  12. 341
  13. 1089
  14. 198
  15. 814
  16. 660
  17. 759
  18. 1199
  19. 803
  20. 935
  21. 968
  22. 198
  23. 374
  24. 407
  25. 682
  26. 594
  27. 880
  28. 1144
  29. 627
  30. 506
  31. 198
  32. 550
  33. 539
  34. 341
  35. 869
  36. 880
  37. 429
  38. 1287
  39. 616
  40. 583

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